wl12xx: use frequency instead of enumerations for pdata clocks

Instead of defining an enumeration with the FW specific values for the
different clock rates, use the actual frequency instead.  Also add a
boolean to specify whether the clock is XTAL or not.

Change all board files to reflect this.

Signed-off-by: Luciano Coelho <luca@coelho.fi>
[Eliad - small fixes, update board file changes]
Signed-off-by: Eliad Peller <eliad@wizery.com>
Tested-by: Nikita Kiryanov <nikita@compulab.co.il>
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>