Driver: Fix the incorrect size of surface 1.

Driver: Fix the incorrect size of surface 1.

According to Ben's comments, the surface 0 and 1 should be exactly
match each other, and the only reason why we need two surfaces rather
than 1 is that for the fulsim usage. Thus we should set surface
1 and 0 with the same memory size.

This patch fixes the flat_address_space unit test case and also
a randome failure reported by yang rong.

Signed-off-by: Zhigang Gong <zhigang.gong@linux.intel.com>
Tested-by: "Yang, Rong R" <rong.r.yang@intel.com>