vdpau: Fix wrong calloc sizeof argument.

vdpau: Fix wrong calloc sizeof argument.

Fix warning reported by Coverity Scan.

Wrong sizeof argument (SIZEOF_MISMATCH)
suspicious_sizeof: Passing argument 3544UL (sizeof
(vlVdpPresentationQueue)) to function calloc that returns a pointer of
type vlVdpPresentationQueueTarget * is suspicious because a multiple of
sizeof (vlVdpPresentationQueueTarget) /*16*/ is expected.

Fixes: 65fe0866aec7 ("vl: implemented a few functions and made stubs to get mplayer running")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3026
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5182>