[PR112918][LRA]: Fixing IRA ICE on m68k

[PR112918][LRA]: Fixing IRA ICE on m68k

Some GCC tests on m68K port of LRA is failed on `maximum number of
generated reload insns per insn achieved`.  The problem is in that for
subreg reload LRA can not narrow reg class more from ALL_REGS to
GENERAL_REGS and then to data regs or address regs.  The patch permits
narowing reg class from reload insns if this results in succesful
matching of reg operand.

gcc/ChangeLog:

	PR rtl-optimization/112918
	* lra-constraints.cc (SMALL_REGISTER_CLASS_P): Move before in_class_p.
	(in_class_p): Restrict condition for narrowing class in case of
	allow_all_reload_class_changes_p.
	(process_alt_operands): Pass true for
	allow_all_reload_class_changes_p in calls of in_class_p.
	(curr_insn_transform): Ditto for reg operand win.