Fix YUV generic C performance function on 24-bit framebuffer

When changed to handle 24-bit framebuffer, some places were missed.

Change-Id: Iaa7e09ea723e5b40bd88b2042c93dafaa7311fee
zen: typo

Change-Id: I68be3c768c092d7e43df8fa233f3a954e56f4d93