archs: replace unifdef-y with header-y

unifdef-y and header-y have same semantic, so drop unifdef-y

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/arch/blackfin/include/asm/Kbuild b/arch/blackfin/include/asm/Kbuild
index 09c3141..d9eb29e 100644
--- a/arch/blackfin/include/asm/Kbuild
+++ b/arch/blackfin/include/asm/Kbuild
@@ -1,4 +1,4 @@
 include include/asm-generic/Kbuild.asm
 
-unifdef-y += bfin_sport.h
-unifdef-y += fixed_code.h
+header-y += bfin_sport.h
+header-y += fixed_code.h