clocksource/drivers/timer-vf-pit: Add missing parenthesis

Recently all usage of setup_irq() was replaced by request_irq(). The
replacement in timer-vf-pit.c missed closing parentheses resulting in a build
error (vf610m4_defconfig). Fix it.

Fixes: cc2550b4

 ("clocksource: Replace setup_irq() by request_irq()")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200323061130.GA6286@afzalpc