arm: socfpga: de0_nano: Probe DWC2 UDC from OF instead of hard-coded data

This patch adds the necessary OF alias for the UDC node, which let's
the code locate the DWC2 UDC base address in OF instead of hard-coding
it into the U-Boot binary. The code is adjusted to use the address from
OF instead of the hard-coded one. Finally, the hard-coded address is
removed and USB DM support is enabled.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Lukasz Majewski <l.majewski@majess.pl>
Cc: Lukasz Majewski <l.majewski@samsung.com>

arch/arm/dts/socfpga_cyclone5_de0_nano_soc.dts

@@ -16,6 +16,7 @@
 
 	aliases {
 		ethernet0 = &gmac1;
+		udc0 = &usb1;
 	};
 
 	memory {
@@ -59,3 +60,7 @@
 	status = "okay";
 	u-boot,dm-pre-reloc;
 };
+
+&usb1 {
+	status = "okay";
+};

configs/socfpga_de0_nano_soc_defconfig

@@ -19,3 +19,5 @@ CONFIG_SYS_NS16550=y
 CONFIG_CADENCE_QSPI=y
 CONFIG_DESIGNWARE_SPI=y
 CONFIG_DM_MMC=y
+CONFIG_USB=y
+CONFIG_DM_USB=y

include/configs/socfpga_de0_nano_soc.h

@@ -56,9 +56,6 @@
 #define CONFIG_ENV_OFFSET		512	/* just after the MBR */
 
 /* USB */
-#ifdef CONFIG_CMD_USB
-#define CONFIG_USB_DWC2_REG_ADDR	SOCFPGA_USB1_ADDRESS
-#endif
 #define CONFIG_G_DNL_MANUFACTURER      "Terasic"
 
 /* Extra Environment */