usb: dwc3: add DWC3_GUCTL1 reg for debug

GUCTL1 reg has some useful functions which can be
written by user. For rockchip platform, we set
GUCTL1.DEV_FORCE_20_CLK_FOR_30_CLK (bit26, applicable
for the core is programmed to operate in 2.0 device
only) to 1 in bootrom, and after start the kernel,
we want to check whether this bit can be reset to
default 0 after the core reset. Dump GUCTL1 reg from
debugfs is more convenient for us.

Signed-off-by: William Wu <william.wu@rock-chips.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -86,6 +86,7 @@
 #define DWC3_GCTL		0xc110
 #define DWC3_GEVTEN		0xc114
 #define DWC3_GSTS		0xc118
+#define DWC3_GUCTL1		0xc11c
 #define DWC3_GSNPSID		0xc120
 #define DWC3_GGPIO		0xc124
 #define DWC3_GUID		0xc128

drivers/usb/dwc3/debugfs.c

@@ -70,6 +70,7 @@ static const struct debugfs_reg32 dwc3_regs[] = {
 	dump_register(GCTL),
 	dump_register(GEVTEN),
 	dump_register(GSTS),
+	dump_register(GUCTL1),
 	dump_register(GSNPSID),
 	dump_register(GGPIO),
 	dump_register(GUID),