bpf, verifier: remove unneeded flow key in check_helper_mem_access

They PTR_TO_FLOW_KEYS is not used today to be passed into a helper
as memory, so it can be removed from check_helper_mem_access().

Signed-off-by: Daniel Borkmann <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>

kernel/bpf/verifier.c

···
 	case PTR_TO_PACKET_META:
 		return check_packet_access(env, regno, reg->off, access_size,
 					   zero_size_allowed);
-	case PTR_TO_FLOW_KEYS:
-		return check_flow_keys_access(env, reg->off, access_size);
 	case PTR_TO_MAP_VALUE:
 		return check_map_access(env, regno, reg->off, access_size,
 					zero_size_allowed);