powerpc/macintosh/smu.c: Fix closing brace followed by if

A closing brace followed by "if" is almost certainly a mistake. Maybe
"else if" was meant, but in this case it doesn't really matter.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>