Let iwx(4) resume directly in DVACT_WAKEUP instead of running the init task.

Let iwx(4) resume directly in DVACT_WAKEUP instead of running the init task.

Suggested by deraadt@ during discussion at k2k21.
With additional input from mlarkin. And deraadt spotted some pointless
splnet() calls which this patch is removing.

Resume from S3 tested by me on an x250 thinkpad with a compatible
ax200 wifi card provided by mlarkin. Hibernate tested by deraadt.

Sync comments about the PCI retry timeout workaround with Linux while here.

ok mlarkin@