drm/panfrost: Put mapping instead of shmem obj on panfrost_mmu_map_fault_addr() error

When panfrost_mmu_map_fault_addr() fails, the BO's mapping should be
unreferenced and not the shmem object which backs the mapping.

Cc: [e-mail]
Fixes: bdefca2d8dc0 ("drm/panfrost: Add the panfrost_gem_mapping concept")
Reviewed-by: Steven Price <[e-mail]>
Signed-off-by: Dmitry Osipenko <[e-mail]>
Signed-off-by: Steven Price <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panfrost/panfrost_mmu.c

···
 err_pages:
 	drm_gem_shmem_put_pages(&bo->base);
 err_bo:
-	drm_gem_object_put(&bo->base.base);
+	panfrost_gem_mapping_put(bomapping);
 	return ret;
 }