powerpc/85xx: enable coreint for all the 64bit boards

With the patch 7230c564 (powerpc: Rework lazy-interrupt handling),
it seems that the coreint works pretty well on the 85xx 64bit kernel.
So use the coreint by default for these boards.

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

diff --cc arch/powerpc/platforms/85xx/p5020_ds.c
Simple merge

diff --cc arch/powerpc/platforms/85xx/p5040_ds.c
Simple merge

diff --cc arch/powerpc/platforms/85xx/t4240_qds.c
Simple merge