Add support for SX151x SPI GPIO Expanders

Signed-off-by: Viktar Palstsiuk <viktar.palstsiuk@promwad.com>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 1165793..b903c45 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -30,3 +30,4 @@
 obj-$(CONFIG_XILINX_GPIO)	+= xilinx_gpio.o
 obj-$(CONFIG_ADI_GPIO2)	+= adi_gpio2.o
 obj-$(CONFIG_TCA642X)		+= tca642x.o
+oby-$(CONFIG_SX151X)		+= sx151x.o