UPSTREAM: usb: gadget: uvc: fix changing interface name via configfs

When setting the function name, it is always truncated by one char since
snprintf is always including the null-termination in the len parameter.
We use strscpy and fix the size setting to use len + 1 instead.

Bug: 254441685
Fixes: 324e4f85 ("usb: gadget: uvc: allow changing interface name via configfs")
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220707115612.2760569-1-m.grzeschik@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 3d0dc539)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Id38f7f27d02c711ca3f1ad5303894912713ef57f