sw64: Do not use timer namespace for timer_shutdown() function

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG



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A new "shutdown" timer state is being added to the generic timer code. One
of the functions to change the timer into the state is called
"timer_shutdown()". This means that there can not be other functions
called "timer_shutdown()" as the timer code owns the "timer_*" name space.

Rename timer_shutdown() to sw64_timer_shutdown() to avoid this conflict.

Signed-off-by: Yu Liao <liaoyu15@huawei.com>