cameraserver hidl: Skip vendor ids with tag count <=0 for getCameraVendorTagSections.

Bug: 199420805

Test: Use getCameraVendorTagSections on devices where a provider returns -1 for getTagCount via vndk

Change-Id: I29f23b6771168ec19c693b2a443f1c9a3fe4c13d
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>