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: 2dfec887 ("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>