firmware: turris-mox-rwtm: Use container_of() instead of hwrng .priv member

Use container_of() to get driver private structure from hwnrg structure,
instead of the hwrng's .priv member, as suggested by Herbert for another
driver.

Link: https://lore.kernel.org/soc/ZmLhQBdmg613KdET@gondor.apana.org.au/Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/20240831092050.23093-14-kabel@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/firmware/turris-mox-rwtm.c

@@ -259,7 +259,7 @@ static int check_get_random_support(struct mox_rwtm *rwtm)
 
 static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
-	struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
+	struct mox_rwtm *rwtm = container_of(rng, struct mox_rwtm, hwrng);
 	struct armada_37xx_rwtm_tx_msg msg;
 	int ret;
 
@@ -487,7 +487,6 @@ static int turris_mox_rwtm_probe(struct platform_device *pdev)
 
 	rwtm->hwrng.name = DRIVER_NAME "_hwrng";
 	rwtm->hwrng.read = mox_hwrng_read;
-	rwtm->hwrng.priv = (unsigned long) rwtm;
 
 	ret = devm_hwrng_register(dev, &rwtm->hwrng);
 	if (ret)