MIPS: lantiq: remove ltq_reset_cause() and ltq_boot_select()

MIPS: lantiq: remove ltq_reset_cause() and ltq_boot_select()

Do not export the ltq_reset_cause() and ltq_boot_select() function any
more. ltq_reset_cause() was accessed by the watchdog driver before to
see why the last reset happened, this is now done through direct access
of the register over regmap. The bits in this register are anyway
different between the xrx200 and the falcon SoC.
ltq_boot_select() is not used any more and was used by the flash
drivers to check if the system was booted from this flash type, now the
drivers should depend on the device tree only.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
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/17126/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>