drm/radeon: Allow write-combined CPU mappings of BOs in GTT (v2)

v2: fix rebase onto drm-fixes

Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --cc drivers/gpu/drm/radeon/cik.c
Simple merge

diff --cc drivers/gpu/drm/radeon/cik_sdma.c
Simple merge

diff --cc drivers/gpu/drm/radeon/evergreen.c
Simple merge

diff --cc drivers/gpu/drm/radeon/r600.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_benchmark.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_device.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_fb.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_gart.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_gem.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_object.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_object.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_prime.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_ring.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_sa.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_test.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_ttm.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_uvd.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_vce.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_vm.c
Simple merge

diff --cc drivers/gpu/drm/radeon/si_dma.c
Simple merge