usb: gadget: update Michal Nazarewicz's email address

The m.nazarewicz@samsung.com email address is no longer valid,
so this commit replaces it with mina86@mina86.com which is
employer-agnostic and thus should be valid for foreseeable
feature.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>