The bike should be fine. A road bike would be faster but you can do a few things to make your current bike better suited for long distance road biking:

1. Optimize the seating position for ergonomics and drag. Make sure your saddle is in the correct position (especially height) so you don’t get knee pain or saddle soreness. Lower the bar as far as comfortable and possible. Maybe get a longer stem if your current setup is relatively short.
2. Get a narrower bar for lower drag.
3. Get bar ends for an additional hand position.
4. Get faster, bald tires, especially if you currently run some mediocre MTB tires.
5. Wear road bike clothes to reduce drag.

The bike should be fine. A road bike would be faster but you can do a few things to make your current bike better suited for long distance road biking:

1. Optimize the seating position for ergonomics and drag. Make sure your saddle is in the correct position (especially height) so you don’t get knee pain or saddle soreness. Lower the bar as far as comfortable and possible. Maybe get a longer stem if your current setup is relatively short.
2. Get a narrower bar for lower drag.
3. Get bar ends for an additional hand position.
4. Get faster, bald slick tires, especially if you currently run some mediocre MTB tires.
5. Wear road bike clothes to reduce drag.