MIPS: OCTEON: Replace SIZEOF_FIELD() macro

In preparation for switching to a standard sizeof_member() macro to find the
size of a member of a struct, remove the custom SIZEOF_FIELD() macro and use
the more common FIELD_SIZEOF() instead. Later patches will globally replace
FIELD_SIZEOF() and sizeof_field() with the more accurate sizeof_member().

Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Link: https://lore.kernel.org/r/20190924105839.110713-4-pankaj.laxminarayan.bharadiya@intel.com


Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>