Convert CONFIG_CMD_HASH to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_HASH

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
[trini: Rework slightly, enable on some boards again]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/freescale/common/Kconfig b/board/freescale/common/Kconfig
index b4bf90d..53b606e 100644
--- a/board/freescale/common/Kconfig
+++ b/board/freescale/common/Kconfig
@@ -1,6 +1,7 @@
 config CHAIN_OF_TRUST
 	depends on !FIT_SIGNATURE && SECURE_BOOT
 	imply CMD_BLOB
+	imply CMD_HASH if ARM
 	select FSL_CAAM
 	select SPL_BOARD_INIT if (ARM && SPL)
 	select SHA_HW_ACCEL