What:		/sys/devices/platform/<renesas_usb3's name>/role
Date:		March 2017
KernelVersion:	4.13
Contact:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Description:
		This file can be read and write.
		The file can show/change the drd mode of usb.

		Write the following string to change the mode:
		 "host" - switching mode from peripheral to host.
		 "peripheral" - switching mode from host to peripheral.

		Read the file, then it shows the following strings:
		 "host" - The mode is host now.
		 "peripheral" - The mode is peripheral now.