r2dplus: fixup CONFIG_SYS_TEXT_BASE to account arch/sh changes

This change allows to reserve enough space at the end of board SDRAM
to store two copies of U-Boot and malloc heap.

Due to selection of the CONFIG_SYS_TEXT_BASE the second code/data
copying is not avoided, first of all this may depend on a used
toolchain, secondly at this point some level of volatility is wanted
to do more platform changes and do not care about probably changed
calculated in runtime relocation offset.
Signed-off-by: NVladimir Zapolskiy <vz@mleia.com>

include/configs/r2dplus.h

@@ -29,7 +29,7 @@
 #define CONFIG_SYS_SDRAM_BASE		0x8C000000
 #define CONFIG_SYS_SDRAM_SIZE		0x04000000
 
-#define CONFIG_SYS_TEXT_BASE		0x8FFC0000
+#define CONFIG_SYS_TEXT_BASE		0x8FE00000
 #define CONFIG_SYS_LONGHELP
 #define CONFIG_SYS_CBSIZE		256
 #define CONFIG_SYS_PBSIZE		256