dtoverlay: Update vc4-kms-dpi-generic for changed mediabus formats

Several of the media bus formats aren't merged upstream yet,
therefore the values change when upstream does introduce
new formats.

As vc4-kms-dpi-generic references the media bus formats explicitly
by number, update it to match.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>