xtensa: Simplify conditional branch/move insn patterns

xtensa: Simplify conditional branch/move insn patterns

No need to describe the "false side" conditional insn patterns anymore.

gcc/ChangeLog:

	* config/xtensa/xtensa-protos.h (xtensa_emit_branch):
	Remove the first argument.
	(xtensa_emit_bit_branch): Remove it because now called only from the
	output statement of *bittrue insn pattern.
	* config/xtensa/xtensa.cc (gen_int_relational): Remove the last
	argument 'p_invert', and make so that the condition is reversed by
	itself as needed.
	(xtensa_expand_conditional_branch): Share the common path, and remove
	condition inversion code.
	(xtensa_emit_branch, xtensa_emit_movcc): Simplify by removing the
	"false side" pattern.
	(xtensa_emit_bit_branch): Remove it because of the abovementioned
	reason, and move the function body to *bittrue insn pattern.
	* config/xtensa/xtensa.md (*bittrue): Transplant the output
	statement from removed xtensa_emit_bit_branch().
	(*bfalse, *ubfalse, *bitfalse, *maskfalse): Remove the "false side"
	insn patterns.