drm/gma500: remove unused variable 'hdmi_ids'

drivers/gpu/drm/gma500/oaktrail_hdmi.c:676:35: warning: ‘hdmi_ids’ defined but not used [-Wunused-const-variable=]
 static const struct pci_device_id hdmi_ids[] = {
                                   ^~~~~~~~

It is never used, remove it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200417101032.8140-1-yuehaibing@huawei.com