Blender Git Loki

Fix T81794: ColorRampElement step regression

Set step in RNA property definition.

There was a hardcoded setting of a1 for this specific button, which
used to be the variable to store the step size of number buttons until
rBe6f0b60c2e91. hardcoded value is removed in rBe29206f86a5f.

Reviewed By: Severin

Differential Revision: https://developer.blender.org/D9277