This will make it easier to change the way logging is done for all
drivers. This also fixes the log category for a couple of drivers as
well as makes failing to set the logger a fatal error. Only when a
logger is already set is it impossible to set another logger.
In the future, this will probably be moved into its own driver, probably
called `intelvtdd` or `intelvfiod`. This is because `acpid` already
provides an interface to read from ACPI tables, which `pcid` has used
for quite long (when that scheme was provided by the kernel). AMD
implements IOMMU as a PCI function, so letting these be separate drivers
would certainly be beneficial.
The same thing might apply for HPET or MADT, which are the only ACPI
tables still parsed in the kernel.
bjorn3