Avoid using error_setg(&error_fatal, ...) in the QEMU sources

According to include/qapi/error.h we should do:

 * Please don't error_setg(&error_fatal, ...), use error_report() and
 * exit(), because that's more obvious.

We still have this pattern in a couple of files, though:

hw/arm/allwinner-a10.c:        error_setg(&error_fatal, "%s: failed to read BlockBackend data",
hw/arm/allwinner-h3.c:        error_setg(&error_fatal, "%s: failed to read BlockBackend data",
hw/arm/allwinner-r40.c:        error_setg(&error_fatal, "%s: failed to read BlockBackend data",
hw/arm/xlnx-versal-virt.c:                error_setg(&error_fatal, "'%s' is either abstract or"
hw/audio/soundhw.c:        error_setg(&error_fatal, "only one -soundhw option is allowed");
system/vl.c:            error_setg(&error_fatal, QERR_MISSING_PARAMETER, "qom-type");

This should get cleaned up to avoid that people copy-n-paste the bad pattern to other parts in the code.