um: chan_xterm: Fix fd leak

um: chan_xterm: Fix fd leak

[ Upstream commit 9431f7c199ab0d02da1482d62255e0b4621cb1b5 ]

xterm serial channel was leaking a fd used in setting up the
port helper

This bug is prehistoric - it predates switching to git. The "fixes"
header here is really just to mark all the versions we would like this to
apply to which is "Anything from the Cretaceous period onwards".

No dinosaurs were harmed in fixing this bug.

Fixes: b40997b872cd ("um: drivers/xterm.c: fix a file descriptor leak")
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>