omap5: Expand CONFIG_SPL_MAX_SIZE and comment upon SRAM_SCRATCH_SPACE_ADDR

After examining both TRMs and doing some experimentation, we can rely on
using the start of the download area for CONFIG_SPL_TEXT_BASE and then
move SRAM_SCRATCH_SPACE_ADDR up, just like am335x.  This is required for
peripheral boot modes such as UART.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/include/configs/omap5_common.h b/include/configs/omap5_common.h
index 8e82fed..0345c57 100644
--- a/include/configs/omap5_common.h
+++ b/include/configs/omap5_common.h
@@ -128,8 +128,8 @@
 
 
 /* Defines for SPL */
-#define CONFIG_SPL_TEXT_BASE		0x40300350
-#define CONFIG_SPL_MAX_SIZE		0x19000	/* 100K */
+#define CONFIG_SPL_TEXT_BASE		0x40300000
+#define CONFIG_SPL_MAX_SIZE		(0x4031E000 - CONFIG_SPL_TEXT_BASE)
 #define CONFIG_SPL_DISPLAY_PRINT
 #define CONFIG_SPL_LDSCRIPT "$(CPUDIR)/omap-common/u-boot-spl.lds"