configs: nitrogen6x: Add DM_GPIO support

Add CONFIG_DM_GPIO to all defconfigs whose board is
nitrogen6x.

mx6qsabrelite_defconfig
nitrogen6dl2g_defconfig
nitrogen6dl_defconfig
nitrogen6q2g_defconfig
nitrogen6q_defconfig
nitrogen6s1g_defconfig

This is in preparation for adding CONFIG_DM_SPI.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/configs/nitrogen6s1g_defconfig b/configs/nitrogen6s1g_defconfig
index 8ad9cc5..f5b1669 100644
--- a/configs/nitrogen6s1g_defconfig
+++ b/configs/nitrogen6s1g_defconfig
@@ -43,6 +43,7 @@
 CONFIG_USB_FUNCTION_FASTBOOT=y
 CONFIG_FASTBOOT_BUF_ADDR=0x12000000
 CONFIG_FSL_USDHC=y
+CONFIG_DM_GPIO=y
 CONFIG_DM_MMC=y
 CONFIG_SPI_FLASH=y
 CONFIG_SF_DEFAULT_MODE=0