Fix two more mips-tdep.h declarations

My earlier patch to fix a declaration mismatch in mips-tdep.h missed a
couple of spots.  Basically, I sent it too soon.

This patch fixes a couple more mismatches between a declaration (using
bfd_vma) and the definition (using CORE_ADDR).

gdb/ChangeLog
2020-02-21  Tom Tromey  <tromey@adacore.com>

	* mips-tdep.h (mips_pc_is_mips16, mips_pc_is_micromips): Parameter
	type is CORE_ADDR.