efikasb/mx: fix usbh1 initialisation

mx51_initialize_usb_hw() support introduced a small error. The usbh1 has
pdev->id equal to 1 not 0, so use pdev->id to make things less error-prone and
to fix that.

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>