openpic: convert simple reg operations to builtin bitops

openpic: convert simple reg operations to builtin bitops

The openpic code has its own bitmap code to access bits inside of a
bitmap. However, that is overkill when we simply want to check for a
bit inside of a uint32_t.

So instead, let's use normal bit masks and C builtin shifts and ands.

Signed-off-by: Alexander Graf <agraf@suse.de>