bootstd: Scan all bootdevs in a boot_targets entry

When the boot_targets environment variable is used with the distro-boot
scripts, each device is included individually. For example, if there
are three mmc devices, then we will have something like:

   boot_targets="mmc0 mmc1 mmc2"

In contrast, standard boot supports specifying just the uclass, i.e.:

   boot_targets="mmc"

The intention is that this should scan all MMC devices, but in fact it
currently only scans the first.

Update the logic to handle this case, without required BOOTSTD_FULL to
be enabled.

I believe at least three people reported this, but I found two.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Date Huang <tjjh89017@hotmail.com>
Reported-by: Vincent Stehlé <vincent.stehle@arm.com>
diff --git a/boot/bootdev-uclass.c b/boot/bootdev-uclass.c
index 974ddee..44ae98a 100644
--- a/boot/bootdev-uclass.c
+++ b/boot/bootdev-uclass.c
@@ -469,10 +469,11 @@
 			 * if no sequence number was provided, we must scan all
 			 * bootdevs for this media uclass
 			 */
-			if (IS_ENABLED(CONFIG_BOOTSTD_FULL) && seq == -1)
+			if (seq == -1)
 				method_flags |= BOOTFLOW_METHF_SINGLE_UCLASS;
 			if (method_flagsp)
 				*method_flagsp = method_flags;
+			log_debug("method flags %x\n", method_flags);
 			return 0;
 		}
 		log_debug("- no device in %s\n", media->name);