locking/spinlocks/mcs: Convert osq lock to atomic_t to reduce overhead
Part of: https://github.com/torvalds/linux/commit/90631822c5d307b5410500806e8ac3e63928aa3e#diff-1
locking/spinlocks/mcs: Introduce and use init macro and function for …
…osq locks
Part of: https://github.com/torvalds/linux/commit/4d9d951e6b5df85ccfca2c5bd8b4f5c71d256b65