MIPS: Netlogic: No need to set -Werror in mips/xlr

The -Werror compilation flag is already set for arch/mips - it can be removed
from arch/mips/xlr/Makefile

Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2963/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>