gpu: ion: Switch to generic map_user function for contig heap
gpu: ion: Switch to generic map_user function for contig heap

There is now a generic map_user function for the contiguous heap.
Move to it rather than reinventing the wheel.

Change-Id: Ibd75640e06d49e01caf39dd4c6d154560f897640
Signed-off-by: Laura Abbott <e7b4910f4742918f5926c991d8a2cd122ac7e295@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas