mbigen: vtimer: isolate mbigen vtimer funcs with macro

virt inclusion
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I8MG11


CVE: NA

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use CONFIG_HISILICON_IRQ_MBIGEN to isolate mbigen vtimer
funcs in ./include/clocksource/arm_arch_timer.h file.

Signed-off-by: Dongxu Sun <sundongxu3@huawei.com>