Rename fridgethr_get to fridgethr_submit

The name fridgethr_get did not make the function's purpose apparent.

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Add per-task cleanup to thread fridge

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Fix up formatting of FSAL_UP

It was a rewrite anyway, so there's nothing we can foreport from 1.5.
It's not that busy an area in the code.
And I'm about to make lots of changes anyway by stuffing it in the fridge.

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Put FSAL UPcall thread in the fridge

And if we find ourselves with lots of upcall traffic, we can trivially
increase the size of the fridge.

Also take the opportunity to simplify upcall dispatch and get rid of
the gigantic switch statements.

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>