I hold both a Sport Pilot License and a Student Pilot certificate. Can I do my BFR in a C-172?
Nope, sorry! If you need a flight review, use an LSA you have been endorsed for.

§61.56(c)(1) states that a flight review must be:


  Accomplished [...] in an aircraft for which that pilot is rated


According to the AOPA (note: this article is specifically targeted at non-Sport pilots):


  Rated is interpreted as category and class [emphasis mine]


And in another article, the AOPA continues:


  Sport pilot certificates will be issued without category/class designation


...and just for the final nail in the coffin, here's the FAA itself (thanks, @Pondlife!), in AC 61-98B:


  A pilot who holds only a sport pilot certificate may only take a flight review in a light sport aircraft for which he or she holds an operational privilege. For example, a sport pilot who holds airplane privileges could not take the flight review in a Cessna 172 since that airplane is not a light sport airplane and he or she does not hold operating privileges for that airplane. 


Long story short, this all means that no, a Sport Pilot cannot perform a flight review in a non-LSA type. Because you require specific logbook endorsements in make/model for category/class/speed (an LSA like a Sting S3 vs Airplane Single-Engine Land), you are not rated to fly a Cessna 172, for example. Your solo endorsement isn't a rating, as it isn't part of a certificate - it's an endorsement.

Once you become a Private Pilot, you'll be able to do a flight review in almost any ASEL type, including all LSAs because you're suddenly rated for the Airplane category and Single Engine Land class, with no light-sport-only limitation.

As far as I can tell, your student pilot certificate is actually invalid. It's been superseded by your Sport Pilot certificate and you are now adding privileges to that certificate. As such, it doesn't really matter that you've been endorsed for solo in a 172; you aren't rated to fly one in the same way you are for an LSA.