MIPS: ralink: Remove unused rt*_wdt_reset functions

MIPS: ralink: Remove unused rt*_wdt_reset functions

All pointers to these functions were removed, so now they produce
warnings:

arch/mips/ralink/rt305x.c:92:13: error: 'rt305x_wdt_reset' defined but not used [-Werror=unused-function]

This removes the functions. If we need them again, the patch can be
reverted later.

Fixes: f576fb6a0700 ("MIPS: ralink: cleanup the soc specific pinmux data")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: John Crispin <john@phrozen.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15044/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>