Don't log when there are no more messages

Throughout input code, we check for presence of messages by looking at
the return code of various read functions. These are usually infinite
reads that get terminated when EWOULDBLOCK is received.

This is guaranteed to be hit every time (otherwise, we would get an
infinite loop). So in this CL, we remove the misleading log about
EWOULDBLOCK, which looks like this:

InputTransport: channel '...WindowInputTests$TestActivity (server)' publisher ~ receiveConsumerResponse: finished: seq=2966, handled=false
InputTransport: channel '...WindowInputTests$TestActivity (server)' publisher ~ receiveConsumerResponse: Unknown error -11

Bug: 282957027
Test: logcatcolor | grep -i input
Change-Id: Ie83fc1c9b69c02d8c48ebebaf4e57e0f76c9a3d9