[lua] Fix hybridDamage mobskill function

[UmeboshiXI]

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What does this pull request do?

Overlooked this since I didn't have it hooked up to anything at the time of testing.

Fixes handleHybridDamage() function used for future hybrid bloodpacts/mobskills.

Steps to test these changes

1. Pick any physical mobskill script. Add the following:
   -- params.hybridSkill = true
   -- params.hybridSkillElement = xi.element.FIRE
   -- params.hybridAttackType = xi.attackType.MAGICAL
   -- params.hybridDamageType = xi.damageType.FIRE

2. execute that script on yourself using !exec target:useMobAbility(skillID, player) on a mob

3. Test Absorb or Nullification on yourself !setmod FIRE_ABSORB 100 or !setmod FIRE_NULL

4. See that NULL mod reduces to 0 and Absorb reduces damage of the skill (You usually won't be able to get it to do more damage than the primary physical damage and actually see the healing message)