usb: imx21-hcd: fix error return code in imx21_probe()

usb: imx21-hcd: fix error return code in imx21_probe()

platform_get_irq() returns an error code, but the imx21-hcd driver
ignores it and always returns -ENXIO. This is not correct, and
prevents -EPROBE_DEFER from being propagated properly.

Notice that platform_get_irq() no longer returns 0 on error:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b739b18b43e38922bad573b28fa83527296f3227

Print error message and propagate the return value of platform_get_irq
on failure.

This issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>