ks_bridge: Use cdev interface instead of misc interface

Using misc device interface may result in deadlock if two drivers
are trying to open/close/register/unregister misc devices
simultaneously. Deadlock is observed when one driver is blocked on
open and another dependent driver is trying to unregister misc
device. To avoid such issues use cdev interface to expose character
device

Change-Id: I5e4a20846027875b0d1556cc28d773968dd0819c
Signed-off-by: Vamsi Krishna <vskrishn@codeaurora.org>