nios2: remove CONFIG_SYS_MALLOC_BASE macro

Remove CONFIG_SYS_MALLOC_BASE macro, as it is not used by
the generic board.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Chin Liang See <clsee@altera.com>

include/configs/nios2-generic.h

@@ -84,8 +84,6 @@
 					 CONFIG_SYS_SDRAM_SIZE - \
 					 CONFIG_SYS_MONITOR_LEN)
 #define CONFIG_SYS_MALLOC_LEN		(CONFIG_ENV_SIZE + 0x20000)
-#define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
-					 CONFIG_SYS_MALLOC_LEN)
 #define CONFIG_SYS_INIT_SP		CONFIG_SYS_MALLOC_BASE
 
 /*