[media] staging: media: davinci_vpfe: Fix spelling error on a comment

Fix spelling error on a comment, change 'wether' to 'whether'

Signed-off-by: Manuel Rodriguez <manuel2982@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>