Make mask value of all 1s.  Value of -1 can't be used for u32 type.

Change-ID: I49d58b77639939fe7447a229dbf1f4a1bf7419ce
Signed-off-by: Kevin Scott <kevin.c.scott@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>