configs: khadas-vim3(l): enable Function button support

Add options required to check the 'Function' button state.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>

configs/khadas-vim3_defconfig

@@ -31,6 +31,8 @@ CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_ADC=y
 CONFIG_SARADC_MESON=y
+CONFIG_BUTTON=y
+CONFIG_BUTTON_ADC=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MESON=y
 CONFIG_DM_MMC=y

configs/khadas-vim3l_defconfig

@@ -31,6 +31,8 @@ CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_ADC=y
 CONFIG_SARADC_MESON=y
+CONFIG_BUTTON=y
+CONFIG_BUTTON_ADC=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MESON=y
 CONFIG_DM_MMC=y