RISCV: config: Remove CFG_SYS_SDRAM_BASE

Remove CFG_SYS_SDRAM_BASE so that we can get DRAM base
from dt instead of compile time config.
Removing this config helps the u-boot more portable.

Signed-off-by: Jimmy Ho <jimmy.ho@sifive.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/include/configs/sifive-unleashed.h b/include/configs/sifive-unleashed.h
index 2996b37..cd8d043 100644
--- a/include/configs/sifive-unleashed.h
+++ b/include/configs/sifive-unleashed.h
@@ -11,7 +11,6 @@
 
 #include <linux/sizes.h>
 
-#define CFG_SYS_SDRAM_BASE		0x80000000
 
 #define RISCV_MMODE_TIMERBASE		0x2000000
 #define RISCV_MMODE_TIMEROFF		0xbff8
diff --git a/include/configs/sifive-unmatched.h b/include/configs/sifive-unmatched.h
index 27e0912..e0064ed 100644
--- a/include/configs/sifive-unmatched.h
+++ b/include/configs/sifive-unmatched.h
@@ -11,6 +11,5 @@
 
 #include <linux/sizes.h>
 
-#define CFG_SYS_SDRAM_BASE		0x80000000
 
 #endif /* __SIFIVE_UNMATCHED_H */