Merge branch 's390-bpf-fix-bpf_arch_text_poke-with-new_addr-null-again'

Ilya Leoshkevich says:

====================
s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL again

This series fixes a regression causing perf on s390 to trigger a kernel
panic.

Patch 1 fixes the issue, patch 2 adds a test to make sure this doesn't
happen again.
====================

Link: https://patch.msgid.link/20250716194524.48109-1-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>