[otbn,dv] Be more explicit in yields in insn.py

It seems that recent versions of mypy complain about "yield" on its
own because they doesn't infer that this is the same as an explicit
"yield None". Tweak the code to match what the tool expects.

Signed-off-by: Rupert Swarbrick <[email protected]>

hw/ip/otbn/dv/otbnsim/sim/insn.py

@@ -261,7 +261,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
         result = state.dmem.load_u32(addr)
 
         # Stall for a single cycle for memory to respond
-        yield
+        yield None
 
         if result is None:
             state.stop_at_end_of_cycle(ErrBits.DMEM_INTG_VIOLATION)
@@ -432,7 +432,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             # value is available, it returns True.
             while not state.wsrs.RND.request_value():
                 # There's a pending EDN request. Stall for a cycle.
-                yield
+                yield None
 
         # At this point, the CSR is ready. Read, update and write back to grs1.
         old_val = state.read_csr(self.csr)
@@ -468,7 +468,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             # value is available, it returns True.
             while not state.wsrs.RND.request_value():
                 # There's a pending EDN request. Stall for a cycle.
-                yield
+                yield None
 
         # At this point, the CSR is either ready or unneeded. Read it if
         # necessary and write to grd, then overwrite with new_val.
@@ -1083,7 +1083,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             state.gprs.get_reg(self.grs1).write_unsigned(new_grs1_val)
 
         # Stall for a single cycle for memory to respond
-        yield
+        yield None
 
         if value is None:
             state.stop_at_end_of_cycle(ErrBits.DMEM_INTG_VIOLATION)
@@ -1140,7 +1140,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             new_grs2_val = grs2_val + 1
             state.gprs.get_reg(self.grs2).write_unsigned(new_grs2_val)
 
-        yield
+        yield None
 
         wrs = grs2_val & 0x1f
         wrs_val = state.wdrs.get_reg(wrs).read_unsigned()
@@ -1210,7 +1210,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             new_grs_val = grs_val + 1
             state.gprs.get_reg(self.grs).write_unsigned(new_grs_val)
 
-        yield
+        yield None
 
         value = state.wdrs.get_reg(wrs).read_unsigned()
         state.wdrs.get_reg(wrd).write_unsigned(value)
@@ -1237,7 +1237,7 @@ def execute(self, state: OTBNState) -> Optional[Iterator[None]]:
             # value is available, it returns True.
             while not state.wsrs.RND.request_value():
                 # There's a pending EDN request. Stall for a cycle.
-                yield
+                yield None
 
         # At this point, the WSR is ready. Does it have a valid value? (It
         # might not if this is a sideload key register and keymgr hasn't