staging: brcm80211: remove otp power control functions

For the devices supported by brcmsmac driver the OTP device is always
powered. Functions for reading power status and changing it are not
needed.

Signed-off-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>