io/lockf: Include bits/types.h before __OFF_T_MATCHES_OFF64_T check

It's possible that although __OFF_T_MATCHES_OFF64_T is defined the
included the relevent header file.  This results in a io/tst-lockf
failure for RV32 by calling the non 64-bit version of lockf.  This
patch fixes the failure by including bits/types.h.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>