Check the service switch on 425e to select apci serial console.

Taken from OpenBSD/hp300.  See the following comment for details:
>> * Check the service switch. On the 425e, this is a physical
>> * switch, unlike other frodo-based machines, so we can use it
>> * as a serial vs internal video selector, since the PROM can not
>> * be configured for serial console.
Fix count vs ret confusion. ret is only set on error when count == 0 -
make sure this is the case.
CID 141398: Fix incorrect test
CID 140077: Add missing break and FALLTHROUGH
CIT 744275: Increase max_retry so we retry once.
add LRO
CID 1203189: Null deref.
CID/1203190: Fix NULL deref
CID/1203191: Out of bounds read
CID/1203192, CID/1203193: Out of bounds read
CID/1203194, CID/1203195: Out of bounds read
CID/1203197: NULL deref
CID/1203196: Don't confuse coverity with out of bounds access
CID/1008347, CID/1008348, CID/1008349:  overflow before widen
CID/1203198, CID/1203199:  Uninitialized scalar variable
Don't free memory; it is used later.
Trash freed memory so we catch bad uses.
typeof and extension don't need parens
Add missing uark and umcs attachments, bump date
s/null/NULL/ to fix build break

Hello, xtos!
put back missing arg