gnss: add mtk receiver type support

Add an MTK (Mediatek) type to the "GNSS_TYPE" attribute.

Note that MTK receivers support a subset of NMEA 0183 with vendor
extensions.

Signed-off-by: Loys Ollivier <lollivier@baylibre.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
diff --git a/drivers/gnss/core.c b/drivers/gnss/core.c
index 4291a0d..320cfca 100644
--- a/drivers/gnss/core.c
+++ b/drivers/gnss/core.c
@@ -334,6 +334,7 @@ static const char * const gnss_type_names[GNSS_TYPE_COUNT] = {
 	[GNSS_TYPE_NMEA]	= "NMEA",
 	[GNSS_TYPE_SIRF]	= "SiRF",
 	[GNSS_TYPE_UBX]		= "UBX",
+	[GNSS_TYPE_MTK]		= "MTK",
 };
 
 static const char *gnss_type_name(struct gnss_device *gdev)
diff --git a/include/linux/gnss.h b/include/linux/gnss.h
index 4354697..36968a0 100644
--- a/include/linux/gnss.h
+++ b/include/linux/gnss.h
@@ -22,6 +22,7 @@ enum gnss_type {
 	GNSS_TYPE_NMEA = 0,
 	GNSS_TYPE_SIRF,
 	GNSS_TYPE_UBX,
+	GNSS_TYPE_MTK,
 
 	GNSS_TYPE_COUNT
 };