selftests/bpf: Update cpumap/devmap sec_name

Substitute deprecated xdp_cpumap and xdp_devmap sec_name with
xdp/cpumap and xdp/devmap respectively in bpf kselftests.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/9a4286cd36781e2c31ba3773bfdcf45cf1bbaa9e.1643727185.git.lorenzo@kernel.org