Revert "net: micrel: fix KS8851_MLL Kconfig"

This reverts commit 1ff5359a which is
commit c3efcedd upstream.

The upstream commit c3efcedd ("net: micrel: fix KS8851_MLL Kconfig")
depends on e5f31552 ("ethernet: fix PTP_1588_CLOCK dependencies")
which is not part of Linux 5.10.y . Revert the aforementioned commit to
prevent breakage in 5.10.y .

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>