kernel: add uinput module

kernel: add uinput module

This module is needed for bluetooth audio playback
with pulseaudio 6 and bluez5.

a working guide can be found in the wiki:
http://wiki.openwrt.org/wiki/bluetooth.audio
(additional packages/modifications are required
and submitted to github feeds)

tested with:
Android mobile (Sony Xperia M) as audio source
TI omap BeagleBoard as audio sink

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45231 3c298f89-4303-0410-b956-a3cf2f4a3e73