soc: apple: rtkit: Make shmem_destroy optional

shmem_destroy isn't always required for coprocessor-managed buffers but we
still enforce that it exists. Just relax the check.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Sven Peter <sven@kernel.org>
Link: https://lore.kernel.org/r/20250610-smc-6-15-v7-4-556cafd771d3@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: svenpeter42

drivers/soc/apple/rtkit.c

@@ -279,8 +279,7 @@ static int apple_rtkit_common_rx_get_buffer(struct apple_rtkit *rtk,
 	dev_dbg(rtk->dev, "RTKit: buffer request for 0x%zx bytes at %pad\n",
 		buffer->size, &buffer->iova);
 
-	if (buffer->iova &&
-	    (!rtk->ops->shmem_setup || !rtk->ops->shmem_destroy)) {
+	if (buffer->iova && !rtk->ops->shmem_setup) {
 		err = -EINVAL;
 		goto error;
 	}