kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig

CONFIG_DEBUG_INFO_SPLIT and CONFIG_DEBUG_INFO_DWARF4 enable extra
dwarf options if supported. You never know if they are really enabled
since Makefile may silently turn them off.

The actual behavior will match to the kernel configuration by
testing those compiler flags in the Kconfig stage.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Makefile b/Makefile
index 0e1f6c3..38c0101 100644
--- a/Makefile
+++ b/Makefile
@@ -742,14 +742,14 @@
 
 ifdef CONFIG_DEBUG_INFO
 ifdef CONFIG_DEBUG_INFO_SPLIT
-DEBUG_CFLAGS	+= $(call cc-option, -gsplit-dwarf, -g)
+DEBUG_CFLAGS	+= -gsplit-dwarf
 else
 DEBUG_CFLAGS	+= -g
 endif
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
 endif
 ifdef CONFIG_DEBUG_INFO_DWARF4
-DEBUG_CFLAGS	+= $(call cc-option, -gdwarf-4,)
+DEBUG_CFLAGS	+= -gdwarf-4
 endif
 
 ifdef CONFIG_DEBUG_INFO_REDUCED