nfsd: stop translating EAGAIN to nfserr_dropit

We no longer need this.

Also, EWOULDBLOCK is generally a synonym for EAGAIN, but that may not be
true on all architectures, so map it as well.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --cc fs/nfsd/nfsproc.c
Simple merge