wcfs: Clarify error context when WatchLink.sendReq is waiting for reply
sendReq has two phases: a) send request, and b) read reply. When there is an error on the first phase, e.g. client does not read what wcfs is trying to send, it returns an error like
pin #2 @03fb63abd6d65b33: sendReq: send .2: context deadline exceeded
however when there is an error on the second phase, e.g. client does not reply to wcfs request, it currently returns an error like
pin #2 @03fb63abd6d65b33: sendReq: context deadline exceeded
which is not clear to interpret about which part was problematic.
After this patch the error for the second case becomes
pin #2 @03fb63abd6d65b33: sendReq: waiting for reply: context deadline exceeded
which is easier to interpret.