This reverts commit 9445725a9e.
Reason for revert: Making ip_protocol mandatory breaks presets in SECURITY_GROUP_RULES (e.g., "All TCP", "SSH" etc) because the field is hidden in the form.
Change-Id: I3a17c8ec60e1004ae96200370791078483308af2
Closes-Bug: #2122416
Signed-off-by: Dmitriy Chubinidze <dcu995@gmail.com>