spl: Convert CONFIG_SPL_ABORT_ON_RAW_IMAGE into a positive option

CONFIG_SPL_ABORT_ON_RAW_IMAGE causes SPL to abort and move on when it
encounters RAW images, express this same functionality as a positive
option enabling support for RAW images: CONFIG_SPL_RAW_IMAGE_SUPPORT

Also move uses of this to defconfigs.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Rework Kconfig logic a little, move to common/spl/Kconfig]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl.c b/common/spl/spl.c
index 2bc8b42..586d75f 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -146,16 +146,18 @@
 		}
 #endif
 
-#ifdef CONFIG_SPL_ABORT_ON_RAW_IMAGE
-		/* Signature not found, proceed to other boot methods. */
-		return -EINVAL;
-#else
+#ifdef CONFIG_SPL_RAW_IMAGE_SUPPORT
 		/* Signature not found - assume u-boot.bin */
 		debug("mkimage signature not found - ih_magic = %x\n",
 			header->ih_magic);
 		spl_set_header_raw_uboot(spl_image);
+#else
+		/* RAW image not supported, proceed to other boot methods. */
+		debug("Raw boot image support not enabled, proceeding to other boot methods");
+		return -EINVAL;
 #endif
 	}
+
 	return 0;
 }