Fixed attack mastery stance skill cooldown mod parser syntax typo

[NL908]

Fixes #7585.

Description of the problem being solved:

• Attack mastery "Stance Skills have +6 seconds to Cooldown" applied to all skills

Steps taken to verify a working solution:

• Rebuild mod cache
• Hold alt to check internal modifiers for the mastery
• Select any skill with no cooldown and there should be no cooldown
• Select any lv1 stance skill and the skill cooldown should be base + 6 seconds

Link to a build that showcases this PR:

https://pobb.in/JjJvNcZ7BdpJ

Before screenshot:

After screenshot: