drm/vmwgfx: Make all surfaces shareable

There is no real need to have a separate pool for shareable and
non-shareable surfaces. Make all surfaces shareable, regardless of whether
the drm_vmw_surface_flag_shareable has been specified.

Signed-off-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240126200804.732454-3-zack.rusin@broadcom.com