drm: don't push static constants on stack for %*ph

There is no need to pass constants via stack. The width may be explicitly
specified in the format.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>