there are mixed questions here:
1) is the practice of islam avodah azarah?
2) even if not, may one enter a mosque
one reason for considering islam avodah zara has to do with the black stone of mecca, which may have or may not have been actually worsipped at one time. and who knows for sure what its status is today. however on the face of it, the muslims do not worship the stone.
discussed in halacha is the problem that the muslims in some countries required the shochet to pronounce kal kabir (which means the same as the phrase quoted above. and I think it is that phrase they were actually required to say).
the quetions revolved around whether it is a hefsek if said after the bracha. not if it avodah zarah.