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.modpost

@@ -72,7 +72,7 @@ $(modules:.ko=.mod.c): __modpost ;
 # Step 5), compile all *.mod.c files
 
 # modname is set to make c_flags define KBUILD_MODNAME
-modname = $(*F)
+modname = $(basetarget)
 
 quiet_cmd_cc_o_c = CC      $@
       cmd_cc_o_c = $(CC) $(c_flags) $(CFLAGS_MODULE)	\