phy: Add Amlogic Meson USB2 & USB3 Generic PHY drivers

The Amlogic Meson GXL and GXM (simple variant) embeds up to 3 USB2 PHYs
and an USB3 PHY. This patch adds drivers for these for the standard generic
PHY interface and supports the power-on/off calls and set the Host mode by
default.
They are based on the excellent work from Martin Blumenstingl merged in linux.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index 68087ae..72c1492 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile
@@ -14,3 +14,4 @@
 obj-$(CONFIG_PHY_SANDBOX) += sandbox-phy.o
 obj-$(CONFIG_$(SPL_)PIPE3_PHY) += ti-pipe3-phy.o
 obj-$(CONFIG_STI_USB_PHY) += sti_usb_phy.o
+obj-$(CONFIG_MESON_GXL_USB_PHY) += meson-gxl-usb2.o meson-gxl-usb3.o