update_kernel: update syslinux before module copy

Otherwise if you switch architectures during the update (32/64-bit), the
module load that's needed to mount the FAT filesystem can't happen (the
module has been replaced with the other binary format).

BUG=none
TEST=run update_kernel on a 32-bit-kernel target after having changed
the overlay to use 64-bit kernel.

Change-Id: I9f302e777a563cbdab2ec636f9a3b35e39ef9c24
Reviewed-on: https://gerrit.chromium.org/gerrit/30681
Tested-by: Olof Johansson <olofj@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Commit-Ready: Olof Johansson <olofj@chromium.org>
1 file changed