bpf: Name the enum for BPF_FUNC_skb_adjust_room flags

The existing anonymous enum for BPF_FUNC_skb_adjust_room flags is
named to enum bpf_adj_room_flags to enable CO-RE (Compile Once -
Run Everywhere) lookups in BPF programs.

Co-developed-by: Max Tottenham <mtottenh@akamai.com>
Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Max Tottenham <mtottenh@akamai.com>
Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
Signed-off-by: Nick Hudson <nhudson@akamai.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20260812083115.73100-2-nhudson@akamai.com

include/uapi/linux/bpf.h

@@ -6283,7 +6283,7 @@ enum {
 };
 
 /* BPF_FUNC_skb_adjust_room flags. */
-enum {
+enum bpf_adj_room_flags {
 	BPF_F_ADJ_ROOM_FIXED_GSO	= (1ULL << 0),
 	BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	= (1ULL << 1),
 	BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	= (1ULL << 2),