wl18xx: fix boot process in high temperature environment

In addition to existing WCS PLL configuration add and enable
also the coex PLL during init phase. This fixes boot failures
due to silicon latchup in high temperature environment (>85c).

Signed-off-by: Victor Goldenshtein <victorg@ti.com>
Signed-off-by: Nadim Zubidat <nadimz@ti.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>