soundwire: cadence: remove unused sdw_cdns_master_ops declaration

sdw_cdns_master_ops has been removed since
commit c91605f4 ("soundwire: Remove cdns_master_ops"),
so remove it.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20220911093442.3221637-1-cuigaosheng1@huawei.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/cadence_master.h

@@ -158,7 +158,6 @@ struct sdw_cdns {
 /* Exported symbols */
 
 int sdw_cdns_probe(struct sdw_cdns *cdns);
-extern struct sdw_master_ops sdw_cdns_master_ops;
 
 irqreturn_t sdw_cdns_irq(int irq, void *dev_id);
 irqreturn_t sdw_cdns_thread(int irq, void *dev_id);