freedreno: fd_bo_from_handle() remove duplicate declaration

Already declared in our public header freedreno_drmif.h

Cc: Rob Clark <robclark@freedesktop.org>
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Acked-by: Rob Clark <robclark@freedesktop.org>