drm/amdgpu: check alignment on CPU page for bo map

commit e3512fb6

 upstream.

The page table of AMDGPU requires an alignment to CPU page so we should
check ioctl parameters for it.  Return -EINVAL if some parameter is
unaligned to CPU page, instead of corrupt the page table sliently.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Xi Ruoyao <xry111@mengyan1223.wang>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>