axi: Add ihs_axi driver

Add a driver for the gdsys IHS AXI bus used on IHS FPGAs.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/drivers/axi/Kconfig b/drivers/axi/Kconfig
index 4e4153b..ae80c98 100644
--- a/drivers/axi/Kconfig
+++ b/drivers/axi/Kconfig
@@ -11,3 +11,15 @@
 	  for now).
 
 	  Other similar bus architectures may be compatible as well.
+
+if AXI
+
+config IHS_AXI
+	bool "Enable IHS AXI driver"
+	depends on DM
+	help
+	  Support for gdsys Integrated Hardware Systems Advanced eXtensible
+	  Interface (IHS AXI) bus on a gdsys IHS FPGA used to communicate with
+	  IP cores in the FPGA (e.g. video transmitter cores).
+
+endif