Remove whitelist entry for CONFIG_GPIO

CONFIG_GPIO does not exist. There is one hit for it in tegra_gpio.c but
it is a variable name.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index 995811c..67e27e4 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -708,7 +708,6 @@
 CONFIG_GMII
 CONFIG_GOOD_SESH4
 CONFIG_GPCNTRL
-CONFIG_GPIO
 CONFIG_GPIO_ENABLE_SPI_FLASH
 CONFIG_GPIO_LED_INVERTED_TABLE
 CONFIG_GPIO_LED_STUBS