cmd: fitupd: move config check to Kconfig

Configuration checks should not be in the C files but in the Kconfig files.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 153864c..192b3b2 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -491,6 +491,7 @@
 
 config CMD_FITUPD
 	bool "fitImage update command"
+	depends on UPDATE_TFTP
 	help
 	  Implements the 'fitupd' command, which allows to automatically
 	  store software updates present on a TFTP server in NOR Flash