Bugfix in ED restart variable name

Fix an error in an ED restart variable name (space instead of
underscore). Problem found by running 'ed' test suite on yellowstone
intel, pgi, gnu. This change fixed a runtime problem with:
ERS_D_Ld5.f19_g16.ICLM45ED.yellowstone_intel.clm-edTest
but there are other tests that fail in the parent changeset.

Test suite: ed yellowstone intel, gnu, pgi
Test baseline: n/a
Test namelist changes: none
Test status: see above.

Fixes see above

Code reviews: self.

main/EDRestVectorMod.F90

@@ -847,7 +847,7 @@ subroutine doVectorIO( this, ncid, flag  )
          readvar=readvar)         
 
 
-    call restartvar(ncid=ncid, flag=flag, varname='ed_chilling days', xtype=ncd_double,  &
+    call restartvar(ncid=ncid, flag=flag, varname='ed_chilling_days', xtype=ncd_double,  &
          dim1name=dimName, &
          long_name='ed chilling day counter', units='unitless', &
          interpinic_flag='interp', data=this%ncd, &