There were always 2 slots used so make no sense to allocate
always dynamically.
Also in this way m_MainMemSlot and m_SurfaceMemSlot become
constant making the code slightly smaller.
Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
Acked-by: Yuri Benditovich <yuri.benditovich@daynix.com>