MIPS: Fix whitespace damage in r4k_wait from VS timer fix

Remove stray spaces/tabs introduced with commit 56651128 ("MIPS: Fix
idle VS timer enqueue") and add missing indentation for a branch delay
slot.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>