configs: pumpkin: enable FIT sha256 support

We are going to start to use sha256 hash. Enable support for it.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
diff --git a/configs/pumpkin_defconfig b/configs/pumpkin_defconfig
index 4adf478..27f3240 100644
--- a/configs/pumpkin_defconfig
+++ b/configs/pumpkin_defconfig
@@ -10,7 +10,6 @@
 # CONFIG_PSCI_RESET is not set
 CONFIG_DEBUG_UART=y
 CONFIG_FIT=y
-# CONFIG_FIT_ENABLE_SHA256_SUPPORT is not set
 # CONFIG_ARCH_FIXUP_FDT_MEMORY is not set
 CONFIG_DEFAULT_FDT_FILE="mt8516-pumpkin"
 # CONFIG_DISPLAY_BOARDINFO is not set