* config/m88k/tm-m88k.h: Fix typo in comment.

	* config/m88k/tm-m88k.h: Fix typo in comment.
	  (FP_REGNUM): define in terms of SP_REGNUM
	  rather than by absolute number.  Also clearly comment that this
	  is a convenient lie in order to decrease future confusion.
	  (ACTUAL_FP_REGNUM): new macro for FP.
	  (FRAME_CHAIN_VALID): removed.  Standard default works fine.
	* m88k-tdep.c (frame_chain_valid): redundant, so removed.
	  (NEXT_PROLOGUE_INSN): removed unused fourth arg, fixed all
	  callers.
	  (read_next_frame_reg): declare static.
	  (examine_prologue): removed unused variabel insn2, rename insn1
	  to insn, rewrote comment about finding fp, sp, etc. set frame_fp
	  based on ACTUAL_FP_REGNUM rather than FP_REGNUM which is
	  actually a scammed alias for SP_REGNUM on m88k.