powerpc/mpic: Remove extra semicolon.

The patch below removes an extra semicolon.

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
CC: linuxppc-dev@lists.ozlabs.org
CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>