drm/amdkfd: bug fix for out of bounds mem on gpu cache filling info

The bitmap in cu_info structure is defined as a 4x4 size array. In
Acturus, this matrix is initialized as a 4x2. Based on the 8 shaders.
In the gpu cache filling initialization, the access to the bitmap matrix
was done as an 8x1 instead of 4x2. Causing an out of bounds memory
access error.
Due to this, the number of GPU cache entries was inconsistent.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>