add missing param names to SkBitmap.h

added names allow doxygen to reference
something

TBR=reed@google.com
Bug: skia:
Change-Id: I816f8e73ba4821356900ceb099404edee390d5b1
Reviewed-on: https://skia-review.googlesource.com/49741
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
1 file changed