msm: kgsl: Correctly update script size for MVC registers

Update crash dumper script size correctly for MVC sub-block
select register so as to avoid out of bound access if any.

Change-Id: I82c4f1ef5f9b8e929ea7d217f6682f96899424bb
Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>