NTA has released an official notification regarding 15% All India Quota. NTA has mentioned that all Candidates are eligible for 15% All India Quota irrespective of the their choice under State of Eligibility. The only exception being Candidates of Jammu and Kashmir and Ladakh because Jammu and Kashmir and Ladakh do not participate in All India Counselling. So in your case, even if you have chosen MP under 15% All India Quota, you can still participate in All India Counselling for all States except for Jammu and Kashmir and Ladakh.