x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS

Add missing semicolon.

Fixes: a74d187c ("x86/entry: Refactor SYS_NI macros")
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200324143520.898733-1-brgerst@gmail.com