The i.MX6Q external memory controller supports eMMC up to rev 4.4/4.41. You may find more information on the i.MX6Q Data Sheet (link below).
http://cache.freescale.com/files/32bit/doc/data_sheet/IMX6DQCEC.pdf
Unfortunately eMMC 5.0 is not supported (along with the HS400 interface which was introduced in this eMMC revision).