ice: add write functionality for GNSS TTY

Add the possibility to write raw bytes to the GNSS module through the
first TTY device. This allows user to configure the module.

Create a second read-only TTY device.

Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>