[SERIAL] Claim Wacom tablet device on HP tc1100 tablet

Claim the WACF005 device.  This is the pen display pointing device on
the HP Compaq tc1100 Tablet PC.  More information about using this
device, including using it as an X pointer device:

    http://www.theory.bham.ac.uk/staff/schofield/linux/tc1100/

Christopher Kemp <ck231@cam.ac.uk> did the legwork of determining that
the WACF005 is really just a plain old UART and doing an initial ACPI
driver (before we had PNPACPI), and David Ludlow <dave@adsllc.com>
confirmed that PNPACPI + the attached patch is now sufficient:

    pnp: Device 00:05 activated.
    ttyS4 at I/O 0x300 (irq = 4) is a 16550A

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>