kbuild: Allow to specify composite modules with modname-m

This allows to write

  drm-$(CONFIG_AGP) += drm_agpsupport.o

without having to handle CONFIG_AGP=y vs. CONFIG_AGP=m. Only support
this syntax for modules, since built-in code depending on something
modular cannot work and init/Makefile actually relies on the current
semantics. There are a few drivers which adapted to the current
semantics out of necessity; these are fixed to also work when the
respective subsystem is modular.

Acked-by: Peter Chen <peter.chen@freescale.com> [chipidea]
Signed-off-by: Michal Marek <mmarek@suse.com>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 01df30a..2c47f9c 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -372,10 +372,14 @@
 #    <composite-object>-objs := <list of .o files>
 #  or
 #    <composite-object>-y    := <list of .o files>
+#  or
+#    <composite-object>-m    := <list of .o files>
+#  The -m syntax only works if <composite object> is a module
 link_multi_deps =                     \
 $(filter $(addprefix $(obj)/,         \
 $($(subst $(obj)/,,$(@:.o=-objs)))    \
-$($(subst $(obj)/,,$(@:.o=-y)))), $^)
+$($(subst $(obj)/,,$(@:.o=-y)))       \
+$($(subst $(obj)/,,$(@:.o=-m)))), $^)
 
 quiet_cmd_link_multi-y = LD      $@
 cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
@@ -390,7 +394,7 @@
 $(multi-used-m): FORCE
 	$(call if_changed,link_multi-m)
 	@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
-$(call multi_depend, $(multi-used-m), .o, -objs -y)
+$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 
 targets += $(multi-used-y) $(multi-used-m)