phy: sun4i-usb: Drop use of arch-specific headers

Since commit 089ffd0a ("phy: sun4i-usb: Use CLK and RESET support")
neither of these headers is used. Dropping them allows the driver to be
architecture-independent.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>