usb: musb: core: fix kernel-doc of musb_init_controller()

Some parameter names in this function's kernel-doc don't match the real
parameters. While at it, give the 'nIrq' parameter slightly more verbose
description.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>