msm: kgsl: use readonly mappings on the iommu
msm: kgsl: use readonly mappings on the iommu

Userspace passes a flag KGSL_MEMFLAGS_GPUREADONLY when
the gpu should not write to a memory region. Use this
flag to control IOMMU_WRITE permissions on the buffer.

Change-Id: I5d3fc615dc36687252e2242f63fe74d6ce1c4fbc
Signed-off-by: Jeremy Gebben <b6cec76cbd1daeeb85b910c75fb55eadc32e8d1b@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