drm/amdgpu: Reset error code for 'no handler' case

If reset handler is not implemented, reset error before proceeding.

Fixes issue with the following trace -
[  106.508592] amdgpu 0000:b1:00.0: amdgpu: ASIC reset failed with error, -38 for drm dev, 0000:b1:00.0
[  106.508972] amdgpu 0000:b1:00.0: amdgpu: GPU reset succeeded, trying to resume
[  106.509116] [drm] PCIE GART of 512M enabled.
[  106.509120] [drm] PTB located at 0x0000008000000000
[  106.509136] [drm] VRAM is lost due to GPU reset!
[  106.509332] [drm] PSP is resuming...

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-and-tested-by: Guchun Chen <guchun.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>