[ Upstream commit 14cf4a77 ]

Telit LE920A4 uses the same pid 0x1201 of LE920, but modem
implementation is different, since it requires DTR to be set for
answering to qmi messages.

This patch replaces QMI_FIXED_INTF with QMI_QUIRK_SET_DTR: tests on
LE920 have been performed in order to verify backward compatibility.
Signed-off-by: Daniele Palmas <dnlplm@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>