BACKPORT: wl12xx: use frequency instead of enumerations for pdata clocks

(cherry picked from 44486b48)

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.

Change-Id: If4be17640a46e93261bd30e8c00c42c7c27d3bc0
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>