target: move sync_cache to struct spc_ops

Add spc_ops->execute_sync_cache() caller for ->execute_cmd() setup,
and update IBLOCK + FILEIO backends to use it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 9b4f2c9..5797b11 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -27,7 +27,6 @@
 
 	int (*parse_cdb)(struct se_cmd *cmd);
 	int (*do_discard)(struct se_device *, sector_t, u32);
-	void (*do_sync_cache)(struct se_cmd *);
 	ssize_t (*check_configfs_dev_params)(struct se_hba *,
 			struct se_subsystem_dev *);
 	ssize_t (*set_configfs_dev_params)(struct se_hba *,
@@ -42,6 +41,7 @@
 
 struct spc_ops {
 	int (*execute_rw)(struct se_cmd *cmd);
+	int (*execute_sync_cache)(struct se_cmd *cmd);
 };
 
 int	transport_subsystem_register(struct se_subsystem_api *);