usb: omap1: Tahvo USB transceiver driver

Add Tahvo USB transceiver driver.

Based on old code from linux-omap tree. The original driver was written
by Juha Yrjölä, Tony Lindgren, and Timo Teräs.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --cc Documentation/ABI/testing/sysfs-platform-tahvo-usb
Simple merge

diff --cc drivers/usb/phy/Kconfig
Simple merge

diff --cc drivers/usb/phy/Makefile
Simple merge

diff --cc drivers/usb/phy/phy-tahvo.c
Simple merge