Set attach type during load for BPF_PROG_TYPE_CGROUP_SKB

As per title, this patch sets `expected_attach_type` during load.

aya/src/programs/cgroup_skb.rs

@@ -62,6 +62,11 @@ pub struct CgroupSkb {
 impl CgroupSkb {
     /// Loads the program inside the kernel.
     pub fn load(&mut self) -> Result<(), ProgramError> {
+        self.data.expected_attach_type = match self.expected_attach_type {
+            Some(CgroupSkbAttachType::Ingress) => Some(BPF_CGROUP_INET_INGRESS),
+            Some(CgroupSkbAttachType::Egress) => Some(BPF_CGROUP_INET_EGRESS),
+            None => None,
+        };
         load_program(BPF_PROG_TYPE_CGROUP_SKB, &mut self.data)
     }