pseries: Update SLOF firmware image to release 20251027

- Fix some measurements in the TPM code
- Fix for compiling with GCC in C23 mode
- Silence some initializer-string warnings with recent GCC

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20251027074404.25758-1-thuth@redhat.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

pc-bios/README

@@ -14,7 +14,7 @@
 - SLOF (Slimline Open Firmware) is a free IEEE 1275 Open Firmware
   implementation for certain IBM POWER hardware.  The sources are at
   https://gitlab.com/slof/slof, and the image currently in qemu is
-  built from git tag qemu-slof-20241106.
+  built from git tag qemu-slof-20251026.
 
 - VOF (Virtual Open Firmware) is a minimalistic firmware to work with
   -machine pseries,x-vof=on. When enabled, the firmware acts as a slim shim and