Remove unnecessary ternary operator in m32c-tdep.c

Remove unnecessary ternary operator in m32c-tdep.c

Bug 17816 pointed out a useless use of the ternary operator:

  case 0x0: sd.reg = (size == 1 ? &st->r0 : &st->r0); break;

I believe that this is right.  If size is 1, the instruction refers to
part of r0, while if size is 2, the instruction refers to the whole of
r0.

gdb/ChangeLog:

	PR gdb/17816
	* m32c-tdep.c (m32c_decode_srcdest4): Remove unnecessary ternary
	operator.