cpufreq: amd-pstate: Remove unnecessary driver_lock in set_boost

In the Linux kernel, the following vulnerability has been resolved: 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.