kernel: fix localversion in v6.3+

kernel: fix localversion in v6.3+

During testing of the v6.4 reference kernel, it was noticed that
on-target modules no longer matched the magic value of the running
kernel.

This was due to a different localversion in the cross built kernel
and the scripts / resources created on target.

This was due to changes in the setlocalversion script introduced
in the v6.3 series.

The .scmversion file is no longer used (or packaged) to inhibit
the addition of a "+" (through querying of the git status of the
kernel) or the setting of a local version.

We recently introduced the KERNEL_LOCALVERSION variable to allow
recipes to place a value in .scmversion, so we extend the use of
that variable to kernel-arch.bbclass and use it to set the
exported variable LOCALVERSION.

We must do it at the kernel-arch level, as the variable must be
exported in any kernel build to ensure that setlocalversion always
correctly sets the localversion.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Cherry-picked from master 765b13b7305c8d2f222cfc66d77c02e6a088c691

Signed-off-by: Andreas Helbech Kleist <andreaskleist@gmail.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>