net: miiphybb: configs: Drop CONFIG_BITBANGMII_MULTI

It seems that every remaining system which enables BITBANGMII also
enables BITBANGMII_MULTI . Remove the BITBANGMII_MULTI symbol and
assume it is always enabled. This allows removal of a bit of legacy
code. No functional change intended.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
17 files changed