Make cam_periph_runccb be safe to call when we can only do polling.

[imp]

Summary

Make cam_periph_runccb() safe for calling when we have to poll. Update
to reflect that cam_periph_runccb() can be called from situations
where the kernel scheduler is stopped, replace the by hand calling of
xpt_polled_action() with it.

Sponsored by: Netflix

[cem]

sys/cam/cam_periph.c

1212

Maybe name it pollwait for consistency with ccbwait. To me poll alone implies checking once, rather than the timeout sleep-wait-retry loop xpt_poll implements.

sys/cam/cam_xpt.c

3249–3250

inconsistent whitespace here

3252

What's the point of passing a timeout argument if it is immediately overwritten?

3256

style(9) nit: whitespace

3263

extra whitespace here

3284

inconsistent whitespace

[imp]

fix review nits

[imp]

sys/cam/cam_xpt.c

3249–3250

the whitespace is now consistent, but phab is having fits with tabs.

3284

It's now consistent, but again, phab is having rendering issues.