ARC: remove CONFIG_ARC_UART_BASE

This macro is defined, but not referenced by anyone.

I did not touch config_whitelist.txt - the CONFIG will be dropped
by the next re-sync.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

include/configs/nsim.h

@@ -30,7 +30,6 @@
  *
  */
 #define CONFIG_ARC_SERIAL
-#define CONFIG_ARC_UART_BASE		0xC0FC1000
 
 /*
  * Command line configuration