Add SR_CONF key for powering off a device

hwdriver.c

@@ -93,6 +93,8 @@ static struct sr_config_info sr_config_info_data[] = {
 		"Hold min", NULL},
 	{SR_CONF_SPL_MEASUREMENT_RANGE, SR_T_UINT64_RANGE, "spl_meas_range",
 		"Sound pressure level measurement range", NULL},
+	{SR_CONF_POWER_OFF, SR_T_BOOL, "power_off",
+		"Power off", NULL},
 	{0, 0, NULL, NULL, NULL},
 };
 

libsigrok.h

@@ -701,6 +701,9 @@ enum {
 	/** The device supports setting the number of probes. */
 	SR_CONF_CAPTURE_NUM_PROBES,
 
+	/** Power off the device. */
+	SR_CONF_POWER_OFF,
+
 	/*--- Acquisition modes ---------------------------------------------*/
 
 	/**