pseries: Update SLOF firmware image

The only change is that SLOF is compiled with -mcpu=power5
to make it work on PPC970 too.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

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://github.com/aik/SLOF, and the image currently in qemu is
-  built from git tag qemu-slof-20211112.
+  built from git tag qemu-slof-20220110.
 
 - 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

roms/SLOF

@@ -1 +1 @@
-Subproject commit a6906b024c6cca5a86496f51eb4bfee3a0c36148
+Subproject commit 5b4c5acdcd552a4e1796aeca6bb700f6cbb0282d