x86: drop extra semi-colon in caa_cpu_relax

This fixes compilation in braceless if/else constructs:

	if (expr)
		caa_cpu_relax();
	else
		...

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>