arm: mvebu: clearfog gtr: add config option to select serdes0 interface

Clearfog GTR has an assembly option for a SATA connector, CON18.
It shares the serdes with mini-pcie connector CON3.

Add new kconfig option to select betweenata and pci, defaulting to pci
as it was previously configured in board-file.

Clearfog GTR connects eth2 / serdes 1 to a 2.5Gbps capable ethernet
switch port. Linux already configures a fixed-link at speed 2500 from
device-tree.
Upgrade serdes 1 rate to 3.125Gbps to support a 2.5Gbps network link on
Clearfog GTR.

Signed-off-by: Josua Mayer <josua@solid-run.com>
diff --git a/board/solidrun/clearfog/clearfog.c b/board/solidrun/clearfog/clearfog.c
index 6fa2fe5..51c5be5 100644
--- a/board/solidrun/clearfog/clearfog.c
+++ b/board/solidrun/clearfog/clearfog.c
@@ -90,9 +90,14 @@
 
 	/* Apply runtime detection changes */
 	if (sr_product_is(&cf_tlv_data, "Clearfog GTR")) {
-		board_serdes_map[0].serdes_type = PEX0;
-		board_serdes_map[0].serdes_speed = SERDES_SPEED_5_GBPS;
-		board_serdes_map[0].serdes_mode = PEX_ROOT_COMPLEX_X1;
+		if (IS_ENABLED(CONFIG_CLEARFOG_GTR_SERDES0_SATA)) {
+			/* serdes 0 is sata (like clearfog pro) */
+		} else if (IS_ENABLED(CONFIG_CLEARFOG_GTR_SERDES0_PCIE)) {
+			/* serdes 0 is pci */
+			board_serdes_map[0].serdes_type = PEX0;
+			board_serdes_map[0].serdes_speed = SERDES_SPEED_5_GBPS;
+			board_serdes_map[0].serdes_mode = PEX_ROOT_COMPLEX_X1;
+		}
 	} else if (sr_product_is(&cf_tlv_data, "Clearfog Pro")) {
 		/* handle recognized product as noop, no adjustment required */
 	} else if (sr_product_is(&cf_tlv_data, "Clearfog Base")) {