drm/i915: don't allow tiling changes on pinned buffers v2
drm/i915: don't allow tiling changes on pinned buffers v2

Makes no sense and complicates matters for pipelined tiling changes.
So don't allow it and return -EBUSY.

v2: Fix reference leak. Thanks to Owain Ainsworth for spotting this.

Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Signed-off-by: Eric Anholt <96f164ad4d9b2b0dacf8ebee2bb1eeb3aa69adf1@anholt.net>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs