kbuild: fix make -rR breakage

make failed to supply the filename when using make -rR and using $(*F)
to get target filename without extension.
This bug was not reproduceable in small scale but using:
$(basename $(notdir $@)) fixes it with same functionality.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/Makefile.build

@@ -117,7 +117,7 @@ $(real-objs-m:.o=.lst): quiet_modtag := [M]
 $(obj-m)              : quiet_modtag := [M]
 
 # Default for not multi-part modules
-modname = $(*F)
+modname = $(basetarget)
 
 $(multi-objs-m)         : modname = $(modname-multi)
 $(multi-objs-m:.o=.i)   : modname = $(modname-multi)