locking: introduce prioritized_section

locking: introduce prioritized_section

Introduce prioritized_section() as a closer match to previous logic
of critical_section() that has been held over longer sequence of
ioctl commands - essentially it's matching operation on a single
cookie.

While 'critical_section()' now corresponds to locked memory - we hold
this memory only between suspend/resume thus notion of 'cookie' was
lost.

This patch restores some logic unintentionaly lost with dropping
memory locking for just activation/deactivation calls.