bpf: offload: rename bpf_offload_dev_match() to bpf_offload_prog_map_match()

A set of new API functions exported for the drivers will soon use
'bpf_offload_dev_' as a prefix.  Rename the bpf_offload_dev_match()
which is internal to the core (used by the verifier) to avoid any
confusion.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>