Even when driver is reloaded and hits this scenario the PSR mutex
should be initialized, otherwise reading PSR debugfs status will
execute mutex_lock() over a mutex that was not initialized.

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190406005112.27205-3-jose.souza@intel.com