ibcore: Simplify ib_modify_qp_is_ok().

All callers to ib_modify_qp_is_ok() provides enum ib_qp_state makes the
checks of out-of-scope redundant. Let's remove them together with updating
function signature to return boolean result.

While at it remove unused "ll" parameter from ib_modify_qp_is_ok().

Linux commit:
19b1f54099b6ee334acbfbcfbdffd1d1f057216d
d31131bba5a1630304c55ea775c48cc84912ab59

Reviewed by: kib
Sponsored by: Mellanox Technologies // NVIDIA Networking

(cherry picked from commit d92a9e5604d7302c349f77c0fde160256aec56ed)