ARM: imx: mach-imx6q: correctly identify i.MX6QP SoCs

The i.MX6QP rev 1.1 SoC on my board is mis-identified by Linux:
the log (incorrectly) shows "i.MX6Q rev 2.1".

Correct this by assuming that every SoC that identifies as
i.MX6Q with rev >= 2.0 is really an i.MX6QP.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>