Modify the RP2040 boot2_w25x10cl.S so it compiles

The label 00: doesn't work with the arm gcc 14.02 from
https://github.com/earlephilhower/pico-quick-toolchain/releases/tag/4.0.1
Changing it to `0:` and the branch statement to `beq 0b` on lines
147 and 150 compiles correctly and hopefully will not brake anything.

src/rp2040/boot_stage2/boot2_w25x10cl.S

@@ -144,10 +144,10 @@ regular_func _stage2_boot
 // status register and checking for the "RX FIFO Not Empty" flag to assert.
 
     movs r1, #SSI_SR_RFNE_BITS
-00:
+0:
     ldr r0, [r3, #SSI_SR_OFFSET]    // Read status register
     tst r0, r1                      // RFNE status flag set?
-    beq 00b                         // If not then wait
+    beq 0b                          // If not then wait
 
 // At this point CN# will be deasserted and the SPI clock will not be running.
 // The Winbond WX25X10CL device will be in continuous read, dual I/O mode and