These are constants, they don't need to be dynamically allocated.
Another minor step towards removing `AK::String` from the Kernel
and improving OOM safety.
Both should reside in the SysFS firmware directory which is normally
located in /sys/firmware.
Also, apply some OOM-safety patterns when creating the BIOS and ACPI
directories.
This will somwhat help unify them also under the same SysFS directory in
the commit.
Also, it feels much more like this change reflects the reality that both
ACPI and the BIOS are part of the firmware on x86 computers.
