scsi: target: Remove unused se_tmr_req_cache declaration

se_tmr_req_cache has been removed since commit c8e31f26 ("target: Add
SCF_SCSI_TMR_CDB usage and drop se_tmr_req_cache").

Remove extern.

Link: https://lore.kernel.org/r/20220913023722.547249-3-cuigaosheng1@huawei.comSigned-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_internal.h

@@ -133,8 +133,6 @@ struct se_node_acl *core_tpg_add_initiator_node_acl(struct se_portal_group *tpg,
 void core_tpg_del_initiator_node_acl(struct se_node_acl *acl);
 
 /* target_core_transport.c */
-extern struct kmem_cache *se_tmr_req_cache;
-
 int	init_se_kmem_caches(void);
 void	release_se_kmem_caches(void);
 u32	scsi_get_new_index(scsi_index_t);