drm/sun4i: frontend: Move the FIR filter phases to our quirks

The FIR filters phase depend on the SoC, so let's move it to our quirks
structure instead of removing them.

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190118145133.21281-22-paul.kocialkowski@bootlin.com