libcopybit: Fix GPU page fault on c2d use

On HDMI connect or other use cases where finish_copybit
is called, reset dst_surface_mapped and dst_surface_base
as destination surface is already unmapped.

Change-Id: I0073a46178e6b1ecfdbf0a08d8790af4271bc37b
CRs-fixed: 481685
CRs-fixed: 502555
1 file changed