tile: use generic-y format for one-line asm-generic headers

This lets us remove a lot of one-line wrapper header files.
See commit d8ecc5cd8e for context.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/include/asm/div64.h

@@ -1 +0,0 @@
-#include <asm-generic/div64.h>