scripts: Move Kconfig contents to cmd/Kconfig

On case-insensitive file systems we have collision between
scripts/kconfig/ directory and scripts/Kconfig file. This patch moves
scripts/Kcofnig contents to cmd/Kconfig to fix that.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 28c91ca..bc4f726 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -116,6 +116,9 @@
 
 source "cmd/fastboot/Kconfig"
 
+config BUILD_BIN2C
+	bool
+
 comment "Commands"
 
 menu "Info commands"