tf-a-ci-gateway: Increase timeout to 4h, allowing to wait for more subjobs

tf-a-ci-gateway doesn't do much beyond waiting for tf-a-builder subjobs.
And with a loaded system, individual tf-a-builder jobs may take longer to
finish. E.g. https://ci.trustedfirmware.org/job/tf-a-ci-gateway/37359/console
where individual tf-a-builder's were sucessful, but took long time, and
tf-a-ci-gateway failed due to timeout without catching the rest of them.
So, increase the timeout by gradual amount.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I2b736609125725974aaa10a829afcebdf83383db
diff --git a/tf-a-ci-gateway.yaml b/tf-a-ci-gateway.yaml
index 710ae1f..405ebb5 100644
--- a/tf-a-ci-gateway.yaml
+++ b/tf-a-ci-gateway.yaml
@@ -26,7 +26,7 @@
           passphrase-variable: ''
     - workspace-cleanup
     - timeout:
-        timeout: 180
+        timeout: 240
         fail: true
     - timestamps
     parameters: