ACPI / EC: Fix code ordering issue in ec_remove_handlers()

There is an order issue in ec_remove_handlers() that acpi_ec_stop()
is called before removing the operation region handler. That is
incorrect, because the operation region handler removal triggers
_REG(DISCONNECT) which may result in new EC transactions to carry
out.

That existing issue has been triggered by the following commit:

    Commit: dcf15cbd
    Subject: ACPI / EC: Fix a boot EC regresion by restoring boot EC

which changed the driver to call ec_remove_handlers() after invoking
_REG(CONNECT), so the issue has become visible.

Fixes: dcf15cbd

 (ACPI / EC: Fix a boot EC regresion by restoring boot EC)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=102421
Reported-and-tested-by: Wolfram Sang <wsa@the-dreams.de>
Reported-by: Nicholas <nkudriavtsev@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>