USB: omap_udc: use devm_request_irq()

The current code fails to release the third irq on the error path
(observed by reading the code), and we get also multiple WARNs with
failing gadget drivers due to duplicate IRQ releases. Fix by using
devm_request_irq().

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