MIPS: ralink: Remove unused timer functions

MIPS: ralink: Remove unused timer functions

The functions were originally used for the module unload path,
but are not referenced any more and just cause warnings:

arch/mips/ralink/timer.c:104:13: error: 'rt_timer_disable' defined but not used [-Werror=unused-function]
arch/mips/ralink/timer.c:74:13: error: 'rt_timer_free' defined but not used [-Werror=unused-function]

Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Fixes: 62ee73d284e7 ("MIPS: ralink: Make timer explicitly non-modular")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: John Crispin <john@phrozen.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15041/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>