serial: Convert ARM_DCC to Kconfig

The symbol "CONFIG_ARM_DCC" is used to control building
drivers/serial/arm_dcc.c.  Provide a simple Kconfig entry for this.

Cc: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Tom McLeod <tom.mcleod@opalkelly.com>
Cc: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
diff --git a/configs/xilinx_zynqmp_mini_nand_defconfig b/configs/xilinx_zynqmp_mini_nand_defconfig
index 01e0971..02d2e29 100644
--- a/configs/xilinx_zynqmp_mini_nand_defconfig
+++ b/configs/xilinx_zynqmp_mini_nand_defconfig
@@ -51,5 +51,6 @@
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_ARASAN=y
 CONFIG_SYS_NAND_MAX_CHIPS=2
+CONFIG_ARM_DCC=y
 CONFIG_PANIC_HANG=y
 # CONFIG_EFI_LOADER is not set