afs: Set error flag rather than return error from file status decode

[ Upstream commit 38355eec6a7d2b8f2f313f9174736dc877744e59 ]

Set a flag in the call struct to indicate an unmarshalling error rather
than return and handle an error from the decoding of file statuses.  This
flag is checked on a successful return from the delivery function.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>