powerpc/b4qds: enable coreint

Commit 9837b43c5f3514e5d28f65f1513f4dc6759d2810 ("powerpc/85xx: enable
coreint for all the 64bit boards") removed the ifdef that avoided
coreint on 64-bit, but it missed b4_qds.c.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Shaveta Leekha <shaveta@freescale.com>