Revert "acpi: mark PMTIMER as unlocked"

This reverts commit 7070e085d490c396f9237c8f10bf8b6e69cd0066.

Commit message claims locking is not needed, but that appears
to not be true, seabios ehci driver runs into timekeeping problems
with this, see
	https://bugzilla.redhat.com/show_bug.cgi?id=1322713

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1460702609-25971-1-git-send-email-kraxel@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
