rxrpc: Fix uninitialised variable in rxrpc_send_data()

rxrpc: Fix uninitialised variable in rxrpc_send_data()

Fix the uninitialised txb variable in rxrpc_send_data() by moving the code
that loads it above all the jumps to maybe_error, txb being stored back
into call->tx_pending right before the normal return.

Fixes: b0f571ecd794 ("rxrpc: Fix locking in rxrpc's sendmsg")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lists.infradead.org/pipermail/linux-afs/2024-October/008896.html
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241001132702.3122709-3-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>