Is Kamala a common name in Tamil?

 Yes.

It is a common name of tamil and telugu families which follow Sri Vaishnavism or Sri Vidya tradition.

Kamala in Sri Vaishnavism refers to Lakshmi in red lotus.

Kamala in Sri Vidya refers to tenth mahavidya and her syllable always represent 16th.

Kamala is a common tamil name in Mainland whereas Island nation uses Shyama, another mahavidya.

Equivalent male name is Kamal, a leading tamil actor.