tqma6: fix sf detection

Commit 155fa9af95ac5be857a7327e7a968a296e60d4c8 changed the way
to define a GPIO line, which can be used to force CS high
across multiple transactions. In order to fix sf detection
change board code to make use of board_spi_cs_gpio(..).

Signed-off-by: Markus Niebel <Markus.Niebel@tq-group.com>
diff --git a/board/tqc/tqma6/tqma6.c b/board/tqc/tqma6/tqma6.c
index b552bb8..fd1bd59 100644
--- a/board/tqc/tqma6/tqma6.c
+++ b/board/tqc/tqma6/tqma6.c
@@ -138,8 +138,10 @@
 	NEW_PAD_CTRL(MX6_PAD_EIM_D18__ECSPI1_MOSI, SPI_PAD_CTRL),
 };
 
+#define TQMA6_SF_CS_GPIO IMX_GPIO_NR(3, 19)
+
 static unsigned const tqma6_ecspi1_cs[] = {
-	IMX_GPIO_NR(3, 19),
+	TQMA6_SF_CS_GPIO,
 };
 
 static void tqma6_iomuxc_spi(void)
@@ -152,6 +154,12 @@
 					 ARRAY_SIZE(tqma6_ecspi1_pads));
 }
 
+int board_spi_cs_gpio(unsigned bus, unsigned cs)
+{
+	return ((bus == CONFIG_SF_DEFAULT_BUS) &&
+		(cs == CONFIG_SF_DEFAULT_CS)) ? TQMA6_SF_CS_GPIO : -1;
+}
+
 static struct i2c_pads_info tqma6_i2c3_pads = {
 	/* I2C3: on board LM75, M24C64,  */
 	.scl = {