wl18xx: update default phy configuration for pg2

default switch configuration set to pg2 chips (rdl 1/2/3/4).
removed hacks for specific board types.
pg1.x boards are now supported only using module params
or specific conf files.

Signed-off-by: Ido Reis <idor@ti.com>
Signed-off-by: Luciano Coelho <luca@coelho.fi>