kbuild: remove unused cmd_none in scripts/Makefile.modinst

Commit 65ce9c38 ("kbuild: move module strip/compression code into
scripts/Makefile.modinst") added this unused code.

Perhaps, I thought cmd_none was useful for CONFIG_MODULE_COMPRESS_NONE,
but I did not use it after all.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

scripts/Makefile.modinst

@@ -28,9 +28,6 @@ modules := $(patsubst $(extmod_prefix)%, $(dst)/%$(suffix-y), $(modules))
 __modinst: $(modules)
 	@:
 
-quiet_cmd_none =
-      cmd_none = :
-
 #
 # Installation
 #