[ARC] Restore blink first when optimizing for speed.

[ARC] Restore blink first when optimizing for speed.

When not optimizing for size, we can restore first blink, hence the return
instruction will be executed faster.

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (GMASK_LEN): Define.
	(arc_restore_callee_saves): Restore first blink when
	!optimize_size.

From-SVN: r270120