phy: sun4i-usb: Control supplies via the regulator uclass

phy: sun4i-usb: Control supplies via the regulator uclass

The device tree binding for the PHY provides VBUS supplies as regulator
references. Now that all boards have the appropriate regulator uclass
drivers enabled, the PHY driver can switch to using them. This replaces
direct GPIO usage, which in some cases needed a special DM-incompatible
"virtual" GPIO from the PMIC.

The following boards provided a value for CONFIG_USB0_VBUS_PIN, but are
missing the "usb0_vbus-supply" property in their device tree. None of
them have the MUSB controller enabled in host or OTG mode, so they
should see no impact:
 - Ainol_AW1_defconfig / sun7i-a20-ainol-aw1
 - Ampe_A76_defconfig / sun5i-a13-ampe-a76
 - CHIP_pro_defconfig / sun5i-gr8-chip-pro
 - Cubieboard4_defconfig / sun9i-a80-cubieboard4
 - Merrii_A80_Optimus_defconfig / sun9i-a80-optimus
 - Sunchip_CX-A99_defconfig / sun9i-a80-cx-a99
 - Yones_Toptech_BD1078_defconfig / sun7i-a20-yones-toptech-bd1078
 - Yones_Toptech_BS1078_V2_defconfig /
   sun6i-a31s-yones-toptech-bs1078-v2
 - iNet_3F_defconfig / sun4i-a10-inet-3f
 - iNet_3W_defconfig / sun4i-a10-inet-3w
 - iNet_86VS_defconfig / sun5i-a13-inet-86vs
 - iNet_D978_rev2_defconfig / sun8i-a33-inet-d978-rev2
 - icnova-a20-swac_defconfig / sun7i-a20-icnova-swac
 - sun8i_a23_evb_defconfig / sun8i-a23-evb

Similarly, the following boards set CONFIG_USB1_VBUS_PIN, but do not
have "usb1_vbus-supply" in their device tree. Neither of them have USB
enabled at all, so again there should be no impact:
 - Cubieboard4_defconfig / sun9i-a80-cubieboard4 (also for USB3)
 - sun8i_a23_evb_defconfig / sun8i-a23-evb

The following boards use a different pin for USB1 VBUS between their
defconfig and their device tree. Depending on which is correct, they
may be broken:
 - Linksprite_pcDuino3_Nano_defconfig (PH11) /
   sun7i-a20-pcduino3-nano (PD2)
 - icnova-a20-swac_defconfig (PG10) / sun7i-a20-icnova-swac (PH6)

Finally, this board has conflicting pins given for its USB2 VBUS:
 - Lamobo_R1_defconfig (PH3) / sun7i-a20-lamobo-r1 (PH12)

Signed-off-by: Samuel Holland <samuel@sholland.org>
[Andre: use regulator_set_enable_if_allowed()]
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>