clocksource/drivers/tcb_clksrc: Make tc_clksrc_suspend/resume() static

Fix sparse warnings:

drivers/clocksource/tcb_clksrc.c:74:6: warning:
 symbol 'tc_clksrc_suspend' was not declared. Should it be static?
drivers/clocksource/tcb_clksrc.c:89:6: warning:
 symbol 'tc_clksrc_resume' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <nicolas.ferre@microchip.com>
Cc: <daniel.lezcano@linaro.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Link: https://lkml.kernel.org/r/20190322143940.12396-1-yuehaibing@huawei.com