driver: serial: fsl_lpuart: support i.MX8ULP

i.MX8ULP lpuart has same register layout as i.MX7ULP and i.MX8

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/include/fsl_lpuart.h b/include/fsl_lpuart.h
index 511fb84..18e5cc1 100644
--- a/include/fsl_lpuart.h
+++ b/include/fsl_lpuart.h
@@ -5,7 +5,7 @@
  */
 
 #if defined(CONFIG_ARCH_MX7ULP) || defined(CONFIG_ARCH_IMX8) || \
-	defined(CONFIG_ARCH_IMXRT)
+	defined(CONFIG_ARCH_IMXRT) || defined(CONFIG_ARCH_IMX8ULP)
 struct lpuart_fsl_reg32 {
 	u32 verid;
 	u32 param;