CVE-2026-93147 s390/bpf: Replace ly instruction with llgf

In the Linux kernel, the following vulnerability has been resolved: s390/bpf: Replace ly instruction with llgf cpunr is a 32 bit value and BPFREG0 is a 64 bit register, when ly loads the cpunr into BPFREG0 it does not zero the upper bits, but llgf does...