linux-phytec-fsl

vgaarb: Use vgaarb: prefix consistently in messages

Define the pr_fmt() macro to causes all messages emitted by pr_*()
functions to be prefixed with "vgaarb: ".

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>