MIPS: lantiq: Remove the arch/mips/lantiq/xway/reset.c implementation

MIPS: lantiq: Remove the arch/mips/lantiq/xway/reset.c implementation

The RCU register are now access through separates drivers. remove the
last pieces of the old implementation.

The GPHY reset bits are now set by the GPHY driver which registers a
reboot notifier. The reboot is triggered by a syscon-reboot driver and
the MIPS specific parts are done by the generic MIPS implementation in
arch/mips/kernel/reset.c.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: john@phrozen.org
Cc: robh@kernel.org
Cc: andy.shevchenko@gmail.com
Cc: p.zabel@pengutronix.de
Cc: kishon@ti.com
Cc: mark.rutland@arm.com
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-watchdog@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-spi@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17131/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>