AVR cc0 conversion - adjust peepholes

AVR cc0 conversion - adjust peepholes

This patch adjusts peepholes to match and generate parallels with
a clobber of REG_CC.

It also sets mov<mode>_insn as the name of the pattern for the split
insn (rather than the define_insn_and_split), so that
avr_2word_insn_p, which looks for CODE_FOR_mov<mode>_insn, works
correctly. This is required for the *cpse.eq peephole to fire, and
also helps generate better code for avr_out_sbxx_branch.

gcc/ChangeLog:

	* config/avr/avr.md: Adjust peepholes to match and
	generate parallels with clobber of REG_CC.
	(mov<mode>_insn): Rename to mov<mode>_insn_split.
	(*mov<mode>_insn): Rename to mov<mode>_insn.