bpf: Selftests and tools use struct bpf_devmap_val from uapi

Sync tools uapi bpf.h header file and update selftests that use
struct bpf_devmap_val.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/159170951195.2102545.1833108712124273987.stgit@firesoul