ACPI: OSL: Add missing __acquires/__releases annotations

Sparse reports a warnings at acpi_os_acquire_lock() and
acpi_os_release_lock():

warning: context imbalance in acpi_os_acquire_lock() - unexpected unlock

warning: context imbalance in acpi_os_release_lock() - unexpected unlock

which result from missing __acquires/__releases annotations.

Add the annotations as appropriate to get rid of the warnings.

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
[ rjw: Two patches merged into one, subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>