cros flash: Fix division type error from CL:1768871

Sample error this fixes:
12:43:27: ERROR: unsupported operand type(s) for /: 'str' and 'int'

BUG=chromium:980619
TEST=cros flash succeeds without the division type error.

Change-Id: I0177de4a9fd39b89151aaa4f6b227abd982c39d5
Signed-off-by: Matthew Blecker <matthewb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1772145
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/cli/flash.py b/cli/flash.py
index 2e5e2ac..db19ae6 100644
--- a/cli/flash.py
+++ b/cli/flash.py
@@ -38,7 +38,7 @@
   def __init__(self, image):
     super(UsbImagerOperation, self).__init__()
     self._size = os.path.getsize(image)
-    self._transferred = 0.
+    self._transferred = 0
     self._bytes = re.compile(r'(\d+) bytes')
 
   def _GetDDPid(self):
@@ -78,7 +78,7 @@
 
     match = self._bytes.search(output)
     if match:
-      self._transferred = match.groups()[0]
+      self._transferred = int(match.groups()[0])
 
     self.ProgressBar(self._transferred / self._size)