drm/amdgpu: set WRITE_BURST_LENGTH to 64B to workaround SDMA1 hang

[ Upstream commit 0c6c8125582714e1fd3544983eba3d750db0f5b8 ]

effect asics: VEGA10 and VEGA12

Signed-off-by: Jim Qu <Jim.Qu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>