firmware_Cr50Update: fix running release_path

The if statement checking that release_ver or release_path exist was
wrong. This change fixes it.

BUG=none
BRANCH=none
TEST=firmware_Cr50Update --args="release_path=$LOCAL_PATH"

Change-Id: I6ff84f400d051836abfcf6420bfe8c349de9e162
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/522875
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
diff --git a/server/site_tests/firmware_Cr50Update/firmware_Cr50Update.py b/server/site_tests/firmware_Cr50Update/firmware_Cr50Update.py
index 8be3dd5..14a6465 100644
--- a/server/site_tests/firmware_Cr50Update/firmware_Cr50Update.py
+++ b/server/site_tests/firmware_Cr50Update/firmware_Cr50Update.py
@@ -53,7 +53,7 @@
             raise error.TestNAError('Test can only be run on devices with '
                                     'access to the Cr50 console')
 
-        if not release_ver or release_path:
+        if not release_ver and not os.path.isfile(release_path):
             raise error.TestError('Need to specify a release version or path')
 
         # Make sure ccd is disabled so it won't interfere with the update