usb: musb: dsps: start OTG timer on resume again

Commit 468bcc2a ("usb: musb: dsps: kill OTG timer on suspend") stopped
the timer in suspend path but forgot the re-enable it in the resume
path. This patch fixes the behaviour.

Cc: <stable@vger.kernel.org> # v3.14+
Fixes 468bcc2a

 "usb: musb: dsps: kill OTG timer on suspend"
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>