Cleanups to FreeBSD/mips native register operations.

Cleanups to FreeBSD/mips native register operations.

Compare against the "raw" PC register number instead of the cooked
register number when determining if a register was handled by
PT_GETREGS.  Previously the register fetch/store operations only tried
PT_GETREGS to fetch any individual register.  The result was that
fetching or storing an individual register not covered by PT_GETREGS
(such as floating point registers) did not work.

While here, remove an early exit to simplify the code flow from the
PT_GETREGS / PT_SETREGS case, and add a getfpregs_supplies similar to
getregs_supplies to describe the registers supplied by PT_GETFPREGS
and PT_SETFPREGS.

gdb/ChangeLog:

	* mips-fbsd-nat.c (getregs_supplies): Fix upper bound comparison.
	(getpfpregs_supplies): New function.
	(mips_fbsd_fetch_inferior_registers): Remove early exit and use
	getfpregs_supplies.
	(mips_fbsd_store_inferior_registers): Likewise.