brcm80211: smac: don't set up tx power limits during initialization

This code is unnecessary, and in fact it's never executed because the
interface is never up when brcms_c_channels_commit() is called. Removing
it helps simplify the implementation of proper regulatory support.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>