rxrpc: Fix leak of released call in recvmsg(MSG_PEEK)

rxrpc: Fix leak of released call in recvmsg(MSG_PEEK)

Fix rxrpc_recvmsg() to also drop the ref it holds on an already-released
call if MSG_PEEK is in force (the function holds a ref on the call
irrespective of whether MSG_PEEK is specified or not).

Fixes: 962fb1f651c2 ("rxrpc: Fix recv-recv race of completed call")
Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-11-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>