serial: Convert ARC_SERIAL to Kconfig

One step closer to completely Kconfig-driven target configuration in
U-Boot :)

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/configs/nsim_700_defconfig b/configs/nsim_700_defconfig
index 12fe5f7..01a461b 100644
--- a/configs/nsim_700_defconfig
+++ b/configs/nsim_700_defconfig
@@ -13,4 +13,5 @@
 CONFIG_OF_EMBED=y
 CONFIG_DM=y
 CONFIG_DM_SERIAL=y
+CONFIG_ARC_SERIAL=y
 CONFIG_USE_PRIVATE_LIBGCC=y
diff --git a/configs/nsim_700be_defconfig b/configs/nsim_700be_defconfig
index 6c0dba7..9188ab2 100644
--- a/configs/nsim_700be_defconfig
+++ b/configs/nsim_700be_defconfig
@@ -14,4 +14,5 @@
 CONFIG_OF_EMBED=y
 CONFIG_DM=y
 CONFIG_DM_SERIAL=y
+CONFIG_ARC_SERIAL=y
 CONFIG_USE_PRIVATE_LIBGCC=y
diff --git a/configs/nsim_hs38_defconfig b/configs/nsim_hs38_defconfig
index bb31adb..58ada45 100644
--- a/configs/nsim_hs38_defconfig
+++ b/configs/nsim_hs38_defconfig
@@ -14,4 +14,5 @@
 CONFIG_OF_EMBED=y
 CONFIG_DM=y
 CONFIG_DM_SERIAL=y
+CONFIG_ARC_SERIAL=y
 CONFIG_USE_PRIVATE_LIBGCC=y
diff --git a/configs/nsim_hs38be_defconfig b/configs/nsim_hs38be_defconfig
index a2cc238..53feb29 100644
--- a/configs/nsim_hs38be_defconfig
+++ b/configs/nsim_hs38be_defconfig
@@ -15,4 +15,5 @@
 CONFIG_OF_EMBED=y
 CONFIG_DM=y
 CONFIG_DM_SERIAL=y
+CONFIG_ARC_SERIAL=y
 CONFIG_USE_PRIVATE_LIBGCC=y
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 5937910..1aab032 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -425,6 +425,13 @@
 	  tree binding to operate, please refer to the document at
 	  doc/device-tree-bindings/serial/qca,ar9330-uart.txt.
 
+config ARC_SERIAL
+	bool "ARC UART support"
+	depends on DM_SERIAL
+	help
+	  Select this to enable support for ARC UART now typically
+	  only used in Synopsys DesignWare ARC simulators like nSIM.
+
 config ATMEL_USART
 	bool "Atmel USART support"
 	help
diff --git a/include/configs/nsim.h b/include/configs/nsim.h
index 0f22606..c3f34a9 100644
--- a/include/configs/nsim.h
+++ b/include/configs/nsim.h
@@ -25,16 +25,6 @@
 #define CONFIG_SYS_LOAD_ADDR		0x82000000
 
 /*
- * UART configuration
- *
- */
-#define CONFIG_ARC_SERIAL
-
-/*
- * Command line configuration
- */
-
-/*
  * Environment settings
  */
 #define CONFIG_ENV_SIZE			SZ_512
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index 9f3ccec..c5cb23d 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -47,7 +47,6 @@
 CONFIG_ARCH_TEGRA
 CONFIG_ARCH_USE_BUILTIN_BSWAP
 CONFIG_ARC_MMU_VER
-CONFIG_ARC_SERIAL
 CONFIG_ARIES_M28_V10
 CONFIG_ARMADA100
 CONFIG_ARMADA100_FEC