staging: vc04_services: Use __func__

This was found using checkpatch.pl's EMBEDDED_FUNCTION_NAME warning.
It is easier to be consistent and always use __func__ instead of having
to remember to update any hardcoded references to the original name.

Signed-off-by: Genki Sky <sky@genki.is>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>