Add unsupported flash layout

This adds an external SPI flash that uses a larger sector size than
the internal flash. Currently this breaks the tests but it's being
added here to trigger a CI fail that will be fixed by adding support
for this feature in a subsequent commit.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/sim/src/lib.rs b/sim/src/lib.rs
index deac61e..7eb27c5 100644
--- a/sim/src/lib.rs
+++ b/sim/src/lib.rs
@@ -388,7 +388,7 @@
             // Simulate nrf52840 with external SPI flash. The external SPI flash
             // has a larger sector size so for now store scratch on that flash.
             let flash0 = SimFlash::new(vec![4096; 128], align as usize, erased_val);
-            let flash1 = SimFlash::new(vec![4096; 128], align as usize, erased_val);
+            let flash1 = SimFlash::new(vec![8192; 64], align as usize, erased_val);
 
             let mut areadesc = AreaDesc::new();
             areadesc.add_flash_sectors(0, &flash0);