n_smux: smux_ctl: Userspace character device interface for SMUX

QMUXD from user-space will use this interface to communicate
control plane QMI messages between APPs and QSC modem in Fusion 4.

Change-Id: I2f51f6927a6f92b106548d22c3965575d4468d5a
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index 3284647..ae5a62c 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -332,6 +332,12 @@
 	help
 	  Provides loopback and unit testing support for the Serial MUX Protocol.
 
+config SMUX_CTL
+	tristate "SMUX control driver"
+	depends on N_SMUX
+	help
+	  Support for SMUX control driver on top of serial MUX.
+
 config TRACE_ROUTER
 	tristate "Trace data router for MIPI P1149.7 cJTAG standard"
 	depends on TRACE_SINK