Update usermod_sn_photoresistor.h

Allow to configure the analog input pin for the Photoresistor.

usermods/SN_Photoresistor/usermod_sn_photoresistor.h

@@ -3,7 +3,9 @@
 #include "wled.h"
 
 //Pin defaults for QuinLed Dig-Uno (A0)
+#ifndef PHOTORESISTOR_PIN
 #define PHOTORESISTOR_PIN A0
+#endif
 
 // the frequency to check photoresistor, 10 seconds
 #ifndef USERMOD_SN_PHOTORESISTOR_MEASUREMENT_INTERVAL