pinctrl: add driver for meson-gxbb pin controller

Add a pin controller driver for Meson GXBB adapted from Linux kernel.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pinctrl/meson/Makefile b/drivers/pinctrl/meson/Makefile
new file mode 100644
index 0000000..6dde4bc
--- /dev/null
+++ b/drivers/pinctrl/meson/Makefile
@@ -0,0 +1,6 @@
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-y					+= pinctrl-meson.o
+obj-$(CONFIG_PINCTRL_MESON_GXBB)	+= pinctrl-meson-gxbb.o