kernel-devsrc: update to v5.4+

kernel-devsrc: update to v5.4+

To support on-target module building, we need to include syscall.tbl
for ARM64 (just like we do for other architectures).

We also copy .config with -a to ensure that we don't trigger extra
processing and regen configs.

Signed-off-by: Bruce Ashfield <bruce.ashfield@xilinx.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>