cifs: eliminate cifs_posix_open_inode_helper

This function is redundant. The only thing it does is set the canCache
flags, but those get set in cifs_new_fileinfo anyway.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>