ACPI / LPSS: provide con_id for the clkdev

Commit 7d78cbef (serial: 8250_dw: add ability to handle
the peripheral clock) introduces handling for a second clk
to 8250_dw.c which is the driver also for LPSS UART. The
second clk forces us to provide identifier (con_id) for the
clkdev we create.

This fixes an issue where 8250_dw.c is getting the same
handler for both clocks.

Fixes: 7d78cbef (serial: 8250_dw: add ability to handle the peripheral clock)
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: 3.17+ <stable@vger.kernel.org> # 3.17+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>