There would be no European colonization of the Americas, since they stumbled upon the New World while looking for a new trade route to the Far East, in order to circumvent Muslim-held Middle East.
Alternatively, the Muslim world, now including Europe, would "discover" the Americas, but I think they'd be more likely to settle on converting the natives and setting up trade posts, than try European-style imperialism.
You're assuming that the Muslim world would be far more united than it was in real life.
There's no reason an Islamic Iberia wouldn't engage in explorations down the coast of Africa much as the Portuguese did. Whether there would be another Western European power to try the longshot of heading west to get to the Indies is a separate issue.
In any case, Tours was more important for the Franks than the Muslims. The failure to take Constantinople a decade and a half earlier did far more to contain the Muslims than did Tours. Even if the Muslims had taken Gaul, it's hard to see where they'd go next from there. The Franks would still control the Rhineland and the Lombards northern Italy.
