cpufreq: amd-pstate: Remove unnecessary driver_lock in set_boost

cpufreq: amd-pstate: Remove unnecessary driver_lock in set_boost

set_boost is a per-policy function call, hence a driver wide lock is
unnecessary. Also this mutex_acquire can collide with the mutex_acquire
from the mode-switch path in status_store(), which can lead to a
deadlock. So, remove it.

Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Acked-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>