drm/ttm: Fix style in ttm_bo_release_mmap()
drm/ttm: Fix a reversed condition and add missing locks

This allows to run OpenGL applications on at least two test machines
with the Radeon driver.

Approved by:	kib@
drm/ttm: Remove unused VM_ALLOC_DMA32 define
drm: Use the new drm_atomic.h, following the merge of projects/atomic64

Submitted by:	jkim@