phy: sun4i-usb: Replace types with explicit quirk flags

So far we were assigning some crude "type" (SoC name, really) to each
Allwinner USB PHY model, then guarding certain quirks based on this.
This does not only look weird, but gets more or more cumbersome to
maintain.

Remove the bogus type names altogether, instead introduce flags for each
quirk, and explicitly check for them.
This improves readability, and simplifies future extensions.

Port of Linux patch 8dd256bae653.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>