kbuild: avoid long argument lists in make modules_install

Running "make modules_install" may fail with

  make[2]: execvp: /bin/sh: Argument list too long

if many modules are built and INSTALL_MOD_PATH is long. This is because
scripts/Makefile.modinst creates all directories with one mkdir command.
Use $(foreach ...) instead to prevent an excessive argument list.

Fixes: 2dfec88 ("kbuild: reduce the number of mkdir calls during modules_install")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Author: mkubecek

scripts/Makefile.modinst

@@ -113,7 +113,7 @@ quiet_cmd_sign :=
 endif
 
 # Create necessary directories
-$(shell mkdir -p $(sort $(dir $(install-y))))
+$(foreach dir, $(sort $(dir $(install-y))), $(shell mkdir -p $(dir)))
 
 $(dst)/%.ko: $(extmod_prefix)%.ko FORCE
 	$(call cmd,install)