drm/amdgpu: unmap and remove csa_va properly

Root PD BO should be reserved before unmap and remove
a bo_va from VM otherwise lockdep will complain.

v2: check fpriv->csa_va is not NULL instead of amdgpu_mcbp (christian)

[14616.936827] WARNING: CPU: 6 PID: 1711 at drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c:1762 amdgpu_vm_bo_del+0x399/0x3f0 [amdgpu]
[14616.937096] Call Trace:
[14616.937097] <TASK>
[14616.937102] amdgpu_driver_postclose_kms+0x249/0x2f0 [amdgpu]
[14616.937187] drm_file_free+0x1d6/0x300 [drm]
[14616.937207] drm_close_helper.isra.0+0x62/0x70 [drm]
[14616.937220] drm_release+0x5e/0x100 [drm]
[14616.937234] __fput+0x9f/0x280
[14616.937239] ____fput+0xe/0x20
[14616.937241] task_work_run+0x61/0x90
[14616.937246] exit_to_user_mode_prepare+0x215/0x220
[14616.937251] syscall_exit_to_user_mode+0x2a/0x60
[14616.937254] do_syscall_64+0x48/0x90
[14616.937257] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: Change AMDGPU_CSA_SIZE to 128K

In order to support new asics and MCBP feature
enablement on baremetal.

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: Move csa related code to separate file

In baremetal, also need to reserve csa for preemption.
so move the csa related code out of sriov.

Reviewed-by: Monk Liu <Monk.Liu@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>