drm/amdgpu: add vram reservation based on vram_usagebyfirmware_v2_2

commit 4864f2ee

 upstream

Move TMR region from top of FB to 2MB for FFBM, so we need to
reserve TMR region firstly to make sure TMR can be allocated at 2MB

Signed-off-by: Tong Liu01 <Tong.Liu01@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>