ARM: i.MX6: add more chip revision support

Add more revision support for the new i.MX6DQ tape-out (TO1.5).  This
TO1.5 is the Rev 1.3 as documented in i.MX6DQ data sheet, because TO1.3
and TO1.4 are never revealed.

Signed-off-by: Jason Liu <r64343@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>