openpic: use standard bitmap operations

openpic: use standard bitmap operations

Besides the private implementation being redundant, namespace collisions
prevented the use of other things in bitops.h.

Serialization does get a bit more awkward, unfortunately, since the
standard bitmap operations are "unsigned long" rather than "uint32_t",
though in exchange we will get faster queue lookups on 64-bit hosts once
we search a word at a time.

Signed-off-by: Scott Wood <[email protected]>
Signed-off-by: Alexander Graf <[email protected]>