i2c: tegra: Add GPCDMA support

Enable support for GPCDMA, which is used in I2C controllers
in Tegra 186 and above. The chips before that used APB DMA.
This change works under the presumption that all chips apart from
those supporting APB DMA is using GPCDMA.

Signed-off-by: Akhil R <[e-mail]>
Reviewed-by: Dmitry Osipenko <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/busses/i2c-tegra.c

···
 	u32 *dma_buf;
 	int err;
 
-	if (!i2c_dev->hw->has_apb_dma || i2c_dev->is_vi)
+	if (i2c_dev->is_vi)
 		return 0;
 
-	if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA)) {
-		dev_dbg(i2c_dev->dev, "DMA support not enabled\n");
+	if (!i2c_dev->hw->has_apb_dma) {
+		if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA)) {
+			dev_dbg(i2c_dev->dev, "APB DMA support not enabled\n");
+			return 0;
+		}
+	} else if (!IS_ENABLED(CONFIG_TEGRA186_GPC_DMA)) {
+		dev_dbg(i2c_dev->dev, "GPC DMA support not enabled\n");
 		return 0;
 	}