ARM: multi_v7_defconfig: Replace DRM_RCAR_HDMI by generic bridge options

The manual bridge implementation was removed in favor of the generic
one, so now we need to enable standard bridge drivers like
DRM_DUMB_VGA_DAC and DRM_I2C_ADV7511.
Both were already enabled, but the (newer) ADV7511 audio part wasn't.

Fixes: 5c602531 ("drm: rcar-du: Replace manual bridge implementation with DRM bridge")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>