misc: atmel-ssc: prepare clock only when request

Prepare SSC clock only when request SSC channel, the clock will be
enabled when initialize the SSC.

Signed-off-by: Bo Shen <[e-mail]>
Acked-by: Nicolas Ferre <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/atmel-ssc.c

···
 	ssc->user++;
 	spin_unlock(&user_lock);
 
-	clk_prepare_enable(ssc->clk);
+	clk_prepare(ssc->clk);
 
 	return ssc;
 }
···
 	spin_unlock(&user_lock);
 
 	if (disable_clk)
-		clk_disable_unprepare(ssc->clk);
+		clk_unprepare(ssc->clk);
 }
 EXPORT_SYMBOL(ssc_free);