serial: exar: Fix GPIO configuration for Sealevel cards based on XR17V35X

serial: exar: Fix GPIO configuration for Sealevel cards based on XR17V35X

Sealevel XR17V35X based devices are inoperable on kernel versions
4.11 and above due to a change in the GPIO preconfiguration introduced in
commit
a8801f7fa94. This patch fixes this by preconfiguring the GPIO on Sealevel
cards to the value (0x00) used prior to commit a8801f7fa94

With GPIOs preconfigured as per commit a8801f7fa94 all ports on
Sealevel XR17V35X based devices become stuck in high impedance
mode, regardless of dip-switch or software configuration. This
causes the device to become effectively unusable. This patch (in
various forms) has been distributed to our customers and no issues
related to it have been reported.

Fixes: a8801f7fa94a ("serial: exar: Preconfigure xr17v35x MPIOs as output")
Signed-off-by: Matthew Howell <matthew.howell@sealevel.com>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2007221605270.13247@tstest-VirtualBox
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>