bpftool: rename is_internal_mmapable_map into is_mmapable_map

bpftool: rename is_internal_mmapable_map into is_mmapable_map

It's not restricted to working with "internal" maps, it cares about any
map that can be mmap'ed. Reflect that in more succinct and generic name.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20240307031228.42896-6-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>