Makefile: Document ability to make file.lst and file.S

Signed-off-by: NJoe Perches <joe@perches.com>
Acked-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Makefile

@@ -1261,7 +1261,9 @@ help:
 	@echo  '  firmware_install- Install all firmware to INSTALL_FW_PATH'
 	@echo  '                    (default: $$(INSTALL_MOD_PATH)/lib/firmware)'
 	@echo  '  dir/            - Build all files in dir and below'
-	@echo  '  dir/file.[ois]  - Build specified target only'
+	@echo  '  dir/file.[oisS] - Build specified target only'
+	@echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
+	@echo  '                    (requires a recent binutils and recent build (System.map))'
 	@echo  '  dir/file.ko     - Build module including final link'
 	@echo  '  modules_prepare - Set up for building external modules'
 	@echo  '  tags/TAGS	  - Generate tags file for editors'