apparmor: remove unused macro

SOCK_ctx() doesn't seem to be used anywhere in the code, so remove it.
Signed-off-by: GONG, Ruiqi <gongruiqi@huaweicloud.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/include/net.h

@@ -52,7 +52,6 @@ struct aa_sk_ctx {
 };
 
 #define SK_CTX(X) ((X)->sk_security)
-#define SOCK_ctx(X) SOCK_INODE(X)->i_security
 #define DEFINE_AUDIT_NET(NAME, OP, SK, F, T, P)				  \
 	struct lsm_network_audit NAME ## _net = { .sk = (SK),		  \
 						  .family = (F)};	  \