kbuild: remove redundant quiet_modtag for $(obj-m)

All objects in $(obj-m) are contained in $(real-obj-m) as well.

It is true composite objects are only contained in $(obj-m),
but [M] is hard-coded in quiet_cmd_link_multi-m.

This line is redundant.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/Makefile.build

@@ -110,8 +110,6 @@ $(real-obj-m:.o=.i)  : quiet_modtag := [M]
 $(real-obj-m:.o=.s)  : quiet_modtag := [M]
 $(real-obj-m:.o=.lst): quiet_modtag := [M]
 
-$(obj-m)             : quiet_modtag := [M]
-
 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
 cmd_cc_s_c       = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<