drm/amdgpu: clean up the amdgpu_cs_parser_bos

drm/amdgpu: clean up the amdgpu_cs_parser_bos

In low memory conditions, kmalloc can fail. In such conditions
unlock the mutex for a clean exit.

We do not need to amdgpu_bo_list_put as it's been handled in the
amdgpu_cs_parser_fini.

Fixes: 737da5363cc0 ("drm/amdgpu: update the functions to use amdgpu version of hmm")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202602030017.7E0xShmH-lkp@intel.com/
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>