powerpc/52xx: fix build breakage for MPC5200 LPBFIFO module

commit 2bf75084f6d9f9a91ba6e30a501ff070d8a1acf6 upstream.

The MPC5200 LPBFIFO driver requires the bestcomm module to be
enabled, otherwise building will fail. Fix it.

Reported-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>