bcachefs: Be more precise with journal error reporting

bcachefs: Be more precise with journal error reporting

We were incorrectly detecting a journal deadlock - the journal filling
up - when only the journal pin fifo had filled up; if the journal pin
fifo is full that just means we need to wait on reclaim.

This plumbs through better error reporting so we can better discriminate
in the journal_res_get path what's going on.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>