gpu: ion: Modify ION_NUM_HEAPS to reflect actual max

ION_NUM_HEAPS is meant to represent the actual max number
of heap types in the system, but currently doesn't reflect
any custom heaps.  This patch changes it to 16.

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Merge branch 'android-3.0' of https://android.googlesource.com/kernel/common into jb_mr1.1_exp