Staging: media: davinci_vpfe: Convert macro 'IPIPE_S12Q8' into inline

Convert macro 'IPIPE_S12Q8' into an inline function to maintain Linux
kernel coding style based on which inline function is preferable to
macro resembling function.

Signed-off-by: Madhumitha Prabakaran <madhumithabiw@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>