Bluetooth: L2CAP: Fix l2cap_global_chan_by_psm

Bluetooth: L2CAP: Fix l2cap_global_chan_by_psm

[ Upstream commit f937b758a188d6fd328a81367087eddbb2fce50f ]

l2cap_global_chan_by_psm shall not return fixed channels as they are not
meant to be connected by (S)PSM.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Reviewed-by: Tedd Ho-Jeong An <tedd.an@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 41e37d04e397ea8dd3bf0e74065703ca6c43c9e9)
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>