mpc83xx: fix global timer structure definition
The byte address distance between GTCFR2 and GTMDR1 is 11, not 10.
Reported-by: Shawn Bai <programassem@hotmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>