cpufreq: make cpufreq_boost_enabled() return bool

cpufreq: make cpufreq_boost_enabled() return bool

Since this function is supposed to return boost_enabled which is anyway
a bool type make sure that it's return value is also marked as bool.
This helps maintain better consistency in data types being used.

Signed-off-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20240627060117.1809477-1-d-gole@ti.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>