m68k: introduce asm/swab.h

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-m68k/Kbuild b/include/asm-m68k/Kbuild
index 1a922fa..52fd96b 100644
--- a/include/asm-m68k/Kbuild
+++ b/include/asm-m68k/Kbuild
@@ -1,2 +1,3 @@
 include include/asm-generic/Kbuild.asm
 header-y += cachectl.h
+unifdef-y += swab.h