powerpc: Replace CONFIG_SYS_INIT_RAM_END with CONFIG_SYS_INIT_RAM_SIZE

CONFIG_SYS_INIT_RAM_SIZE may be used out of the board header file.
Some boards use CONFIG_SYS_INIT_RAM_END for the same purpose. To
unify the macros, use CONFIG_SYS_INIT_RAM_SIZE for all.

Signed-off-by: York Sun <york.sun@nxp.com>
CC: Mario Six <mario.six@gdsys.cc>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Anatolij Gustschin <agust@denx.de>
diff --git a/include/configs/io.h b/include/configs/io.h
index 1213fe2..f05eb0a 100644
--- a/include/configs/io.h
+++ b/include/configs/io.h
@@ -196,10 +196,10 @@
 #define CONFIG_SYS_OCM_DATA_ADDR	0xF8000000
 #define CONFIG_SYS_OCM_DATA_SIZE	0x1000
 #define CONFIG_SYS_INIT_RAM_ADDR	CONFIG_SYS_OCM_DATA_ADDR /* in SDRAM */
-#define CONFIG_SYS_INIT_RAM_END	CONFIG_SYS_OCM_DATA_SIZE /* End of used area */
+#define CONFIG_SYS_INIT_RAM_SIZE	CONFIG_SYS_OCM_DATA_SIZE
 
 #define CONFIG_SYS_GBL_DATA_OFFSET \
-	(CONFIG_SYS_INIT_RAM_END - GENERATED_GBL_DATA_SIZE)
+	(CONFIG_SYS_INIT_RAM_SIZE - GENERATED_GBL_DATA_SIZE)
 #define CONFIG_SYS_INIT_SP_OFFSET	CONFIG_SYS_GBL_DATA_OFFSET
 
 /*