netfilter: xt_qtaguid: xt_socket: build fixes

Add missing header <linux/miscdevice.h> and use
xt_socket_lookup_slow_v* instead of xt_socket_get*_sk
in xt_qtaguid.c.

Fix xt_socket_lookup_slow_v* functions in xt_socket.c
and declare them in xt_socket.h

Change-Id: I55819b2d4ffa82a2be20995c87d28fb5cc77b5ba
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>