powerpc/stacktrace: Update copyright

This now has new code in it written by Nick and I, and switch to a
SPDX tag.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Michael Ellerman 2018-05-02 23:07:29 +10:00
commit 7af76c5f23