tap_common:Add passivly starting the PWM rgbled driver

Board builds may now inclulde both the PWM and I2C RGB LED
    To add the PWM RGB LED driver:The board must define
    BOARD_HAS_LED_PWM and include rgbled_pwm the moulde list.

    This change attempts to start the either rgbled driver, that
    may or may not be present. If it is not present the +e
    setting allows the start up to continue.

ROMFS/tap_common/init.d/rcS

@@ -74,6 +74,10 @@ tone_alarm start
 #
 # Start system state indicator
 #
+if rgbled_pwm start
+then
+fi
+
 if rgbled start
 then
 fi