It was pointed out by 'make versioncheck' that linux/version.h was not
always being included where needed and sometimes included needlessly
in drivers/usb/.
This patch fixes up the includes.

For the UVC gadget driver bits, this was ACK'ed by Laurent Pinchart.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>