flash_can: add retries to verification

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

scripts/flash_can.py

@@ -158,9 +158,14 @@ class CanFlasher:
                 if resp == i:
                     # command should ack with the requested block as
                     # parameter
+                    try:
                         buf = await self.node.readexactly(
-                        self.block_size, timeout=10.
+                            self.block_size, timeout=5.
                         )
+                    except asyncio.TimeoutError:
+                        if tries:
+                            output_line("\nRead Timeout, Retrying...")
+                    else:
                         if len(buf) == self.block_size:
                             break
                 tries -= 1