drm/vmwgfx: replace drm_*_unreference with drm_*_put

This patch replace instances of drm_framebuffer_unreference with _put()
suffix, because it is shorter and consistent with the kernel use of
*_get/put() suffixes.
This was done with the following Coccinelle script:

@r@
expression e;
@@

(
-drm_framebuffer_reference(e);
+drm_framebuffer_get(e);
|
-drm_framebuffer_unreference(e);
+drm_framebuffer_put(e);
)

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Acked-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180311233313.GA19721@Haneen