staging: rtl8723au: Remove a pile of unused EFUSE read/write functionality

All this code was only pulled in since it was registered in the HAL
wrapper interface, despite it never being called. It also removes the
lasts pieces of code from rtl8723a_set_hal_ops(), so remove it as
well.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>