Revert "arm: mx6_c1: Restore Gate Registers from 2009 U-Boot"

As I had experienced in previous dev work some other testers have
seen instability with these timings.  Revert this patch and go
back to the clock gates used by the default sabresd boards.

This reverts commit 534b810c93d8617089ace430cc01bc1099e1be66.