ARM: 7051/1: cpuimx* boards: fix mach-types errors

I made some changes to the entry in the ARM Machine Registry after
submission which was the wrong thing to do.
This patch should help to fix this error.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>