Only use NO_REGS in cost calculation when !hard_regno_mode_ok for GENERAL_REGS and...

Only use NO_REGS in cost calculation when !hard_regno_mode_ok for GENERAL_REGS and mode.

r14-172-g0368d169492017 replaces GENERAL_REGS with NO_REGS in cost
calculation when the preferred register class are not known yet.
It regressed powerpc PR109610 and PR109858, it looks too aggressive to use
NO_REGS when mode can be allocated with GENERAL_REGS.
The patch takes a step back, still use GENERAL_REGS when
hard_regno_mode_ok for mode and GENERAL_REGS, otherwise uses NO_REGS.

gcc/ChangeLog:

	PR target/109610
	PR target/109858
	* ira-costs.cc (scan_one_insn): Only use NO_REGS in cost
	calculation when !hard_regno_mode_ok for GENERAL_REGS and
	mode, otherwise still use GENERAL_REGS.