smb: client: fix warning in CIFSFindFirst()

This fixes the following warning reported by kernel test robot

  fs/smb/client/cifssmb.c:4089 CIFSFindFirst() warn: missing error
  code? 'rc'

Link: https://lore.kernel.org/all/202306170124.CtQqzf0I-lkp@intel.com/


Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>