MLK-24192-1 lpuart: Enable IPG clock

Current codes only ennable the PER clock. However on iMX8 the LPUART
also needs IPG clock which is an LPCG. Should not depend on the default
LPCG setting.

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
(cherry picked from commit 117c616)
(cherry picked from commit 0108adc)
(cherry picked from commit dc0789d8fbd16d095ffe0271506dfd725cb4407f)

drivers/serial/serial_lpuart.c

@@ -480,18 +480,30 @@ static int lpuart_serial_probe(struct udevice *dev)
 {
 #if CONFIG_IS_ENABLED(CLK)
 	struct clk per_clk;
+	struct clk ipg_clk;
 	int ret;
 
 	ret = clk_get_by_name(dev, "per", &per_clk);
 	if (!ret) {
 		ret = clk_enable(&per_clk);
 		if (ret) {
-			dev_err(dev, "Failed to get per clk: %d\n", ret);
+			dev_err(dev, "Failed to enable per clk: %d\n", ret);
 			return ret;
 		}
 	} else {
 		debug("%s: Failed to get per clk: %d\n", __func__, ret);
 	}
+
+	ret = clk_get_by_name(dev, "ipg", &ipg_clk);
+	if (!ret) {
+		ret = clk_enable(&ipg_clk);
+		if (ret) {
+			dev_err(dev, "Failed to enable ipg clk: %d\n", ret);
+			return ret;
+		}
+	} else {
+		debug("%s: Failed to get ipg clk: %d\n", __func__, ret);
+	}
 #endif
 
 	if (is_lpuart32(dev))