drm/amdgpu: Remove else after return statement in 'gmc_v8_0_check_soft_reset'

Fix below checkpatch warnings:

WARNING: else is not generally useful after a break or return
+               return true;
+       } else {

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>