Clang Static Analyzer version 8.0.0 detects access to field dev results
in a dereference of a null pointer which is loaded from variable bus.
Add sanity check for pointer bus to prevent null pointer dereference.
TEST=Built and boot up to kernel.
Change-Id: I084906c33065eaa834f50c545efcfab620658ec9
Signed-off-by: John Zhao <john.zhao@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33101
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Lijian Zhao <lijian.zhao@intel.com>