Microblaze cacheline length is configurable and current cpu
uses two cacheline length 4 and 8.
We are taking conservative maximum value to be sure that cacheline
alignment is satisfied for all cases.
Here is the calculation for cacheline lenght 8 32bit=4Byte values
which is corresponding with SHIFT 5.
Signed-off-by: Michal Simek <monstr@monstr.eu>