drm/amdgpu: change the alignment size of TMR BO to 1M

align TMR BO size TO tmr size is not necessary,
modify the size to 1M to avoid re-create BO fail
when serious VRAM fragmentation.

v2:
add new macro PSP_TMR_ALIGNMENT for TMR BO alignment size

Signed-off-by: Yang Wang <KevinYang.Wang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>