scripts/runfvp: fix silent failure when FVP is missing

Print an error message if the FVP binary cannot be found, instead of
failing silently.

Signed-off-by: Roger Knecht <roger.knecht@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

scripts/runfvp

@@ -77,7 +77,8 @@ def start_fvp(args, fvpconf, extra_args):
         else:
             for line in fvp.stdout:
                 print(line.strip().decode(errors='ignore'))
-
+    except FileNotFoundError as e:
+        logger.error(f"FVP executable not found ({e})")
     finally:
         return fvp.stop()