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/configs/bcm958622hr_defconfig b/configs/bcm958622hr_defconfig
index 9ffbe4b..c2713c6 100644
--- a/configs/bcm958622hr_defconfig
+++ b/configs/bcm958622hr_defconfig
@@ -13,6 +13,7 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIME=y
+CONFIG_CMD_HASH=y
 CONFIG_CMD_FAT=y
 # CONFIG_MMC is not set
 CONFIG_SYS_NS16550=y