serial/serial_arc - add driver for ARC UART

Driver for non-standard on-chip UART, instantiated in the ARC (Synopsys)
FPGA Boards such as ARCAngel4/ML50x

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Mischa Jonker <mjonker@synopsys.com>
Cc: Francois Bedard <fbedard@synopsys.com>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index df2b84a..05cb369 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -160,6 +160,7 @@
 serial_initfunc(sh_serial_initialize);
 serial_initfunc(arm_dcc_initialize);
 serial_initfunc(mxs_auart_initialize);
+serial_initfunc(arc_serial_initialize);
 
 /**
  * serial_register() - Register serial driver with serial driver core
@@ -253,6 +254,7 @@
 	sh_serial_initialize();
 	arm_dcc_initialize();
 	mxs_auart_initialize();
+	arc_serial_initialize();
 
 	serial_assign(default_serial_console()->name);
 }