ARM: pxa/lubbock: add pcmcia clock

Add the required PCMCIA clock for the SA1111 "1800" device.  This clock
is used to compute timing information for the PCMCIA interface in the
SoC device, rather than the SA1111.  Hence, the provision of this clock
is a convenience for the driver and does not reflect the hardware, so
this must not be copied into DT.

Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>