usb: gadget: push iManufacturer into gadgets

This patch pushes the iManufacturer module argument from composite into
each gadget. Once the user uses the module paramter, the string is
overwritten with the final value.

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>