ARM: Add unwinding annotations to __loop.*delay functions

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8MTBB


CVE: NA

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The unwind directives can't handle nested function entries, so only the
outermost function __loop_udelay is annotated, and the inner nested
entries share the same unwind info with __loop_udelay.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Reviewed-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>