sysreset: Add poweroff-gpio driver

Add GPIO poweroff driver, which is based on the Linux
driver and uses the same DT binding.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
diff --git a/drivers/sysreset/Makefile b/drivers/sysreset/Makefile
index 920c692..de81c39 100644
--- a/drivers/sysreset/Makefile
+++ b/drivers/sysreset/Makefile
@@ -7,6 +7,7 @@
 obj-$(CONFIG_ARCH_ROCKCHIP) += sysreset_rockchip.o
 obj-$(CONFIG_ARCH_STI) += sysreset_sti.o
 obj-$(CONFIG_SANDBOX) += sysreset_sandbox.o
+obj-$(CONFIG_POWEROFF_GPIO) += poweroff_gpio.o
 obj-$(CONFIG_SYSRESET_GPIO) += sysreset_gpio.o
 obj-$(CONFIG_SYSRESET_MPC83XX) += sysreset_mpc83xx.o
 obj-$(CONFIG_SYSRESET_MICROBLAZE) += sysreset_microblaze.o