cpufreq: schedutil: Rectify comment in sugov_irq_work() function

This patch rectifies a comment present in sugov_irq_work() function to
follow proper grammar.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>