sim: Remove complexity from an if

Clippy suggests that having a closure in the condition of an if can be
confusing in regards to code formatting.  Move the conditional outside
of the if into a temp variable.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/image.rs b/sim/src/image.rs
index cfe20b5..c420645 100644
--- a/sim/src/image.rs
+++ b/sim/src/image.rs
@@ -1564,11 +1564,14 @@
         // aren't marked as the BootLoader partition, avoid adding the
         // partition table.  This makes it harder to view the image, but
         // avoids messing up images already written.
-        if areadesc.iter_areas().any(|area| {
-            area.device_id == id &&
-                area.off == 0 &&
-                area.flash_id != FlashId::BootLoader
-        }) {
+        let skip_ptable = areadesc
+            .iter_areas()
+            .any(|area| {
+                area.device_id == id &&
+                    area.off == 0 &&
+                    area.flash_id != FlashId::BootLoader
+            });
+        if skip_ptable {
             if log_enabled!(Info) {
                 let special: Vec<FlashId> = areadesc.iter_areas()
                     .filter(|area| area.device_id == id && area.off == 0)