[MIPS] Kill redundant EXTRA_AFLAGS

Kill redundant EXTRA_AFLAGS added after the commit
d2af363cfb94f1bacb3e60327bc44a97881a38c2.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2 files changed