datapath: Use sizeof_field macro

datapath: Use sizeof_field macro

Upstream commit:
    commit c593642c8be046915ca3a4a300243a68077cd207
    Author: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
    Date:   Mon Dec 9 10:31:43 2019 -0800

    treewide: Use sizeof_field() macro

    Replace all the occurrences of FIELD_SIZEOF() with sizeof_field() except
    at places where these are defined. Later patches will remove the unused
    definition of FIELD_SIZEOF().

    This patch is generated using following script:

    EXCLUDE_FILES="include/linux/stddef.h|include/linux/kernel.h"

    git grep -l -e "\bFIELD_SIZEOF\b" | while read file;
    do

    	if [[ "$file" =~ $EXCLUDE_FILES ]]; then
    		continue
    	fi
    	sed -i  -e 's/\bFIELD_SIZEOF\b/sizeof_field/g' $file;
    done

    Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Link: https://lore.kernel.org/r/20190924105839.110713-3-pankaj.laxminarayan.bharadiya@intel.com
    Co-developed-by: Kees Cook <keescook@chromium.org>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Acked-by: David Miller <davem@davemloft.net> # for net
Also added a compatibility layer macro for older kernels that still
use FIELD_SIZEOF

Acked-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>