x86: Tidy up address for loading U-Boot from SPL

Use the binman symbols for this, to avoid hard-coding the value. We could
use CONFIG_X86_OFFSET_U_BOOT for the address, but it seems better to
obtain the offset and size through the same mechanism.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/spl.c b/arch/x86/lib/spl.c
index 5e47ffa..479889a 100644
--- a/arch/x86/lib/spl.c
+++ b/arch/x86/lib/spl.c
@@ -217,16 +217,9 @@
 	spl_image->name = "U-Boot";
 
 	if (!IS_ENABLED(CONFIG_SYS_COREBOOT)) {
-		/*
-		 * Copy U-Boot from ROM
-		 * TODO(sjg@chromium.org): Figure out a way to get the text base
-		 * correctly here, and in the device-tree binman definition.
-		 *
-		 * Also consider using FIT so we get the correct image length
-		 * and parameters.
-		 */
-		memcpy((char *)spl_image->load_addr, (char *)0xfff00000,
-		       0x100000);
+		/* Copy U-Boot from ROM */
+		memcpy((void *)spl_image->load_addr,
+		       (void *)spl_get_image_pos(), spl_get_image_size());
 	}
 
 	debug("Loading to %lx\n", spl_image->load_addr);