ARM: dts: imx28: add pinmux for USB1 overcurrent on pwm2

Add pinmux setting for USB1 overcurrent on pwm2 pad.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>