layout: Add capacity field

Use it to keep track of the size of the `entries` array. An interim
solution until we have dynamic allocation.

Change-Id: Ib5f431bc0a72a79a53fa1376c3417942b19dd3a0
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/33516
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

flashrom.c

@@ -825,6 +825,7 @@ notfound:
 	/* Fill fallback layout covering the whole chip. */
 	struct single_layout *const fallback = &flash->fallback_layout;
 	fallback->base.entries		= &fallback->entry;
+	fallback->base.capacity		= 1;
 	fallback->base.num_entries	= 1;
 	fallback->entry.start		= 0;
 	fallback->entry.end		= flash->chip->total_size * 1024 - 1;