Hello

See it all depends on your intrest if you want to learn coding you can learn it anyway there are lots of online sites from where you can learn coding , coming to your question i would suggest you to go for mechanical in tier 2 college because as you have mentioned you are intrested in coding only you can learn it in mechanical branch also through online site at the same time you will also get the knowledge about mechanical field as well which will be benifical for you in future .

here are few platform from where you can learn coding

1. udemy

2.sololearn

3. youtube channel

Thank you

Good luck