staging: pi433: Fix missing 'undefined' value in enum modulation

It is possible that rf69_get_modulation() function will return
'undefined' value and this value is missing in enum modulation. Fix this
by adding appropriate entry in enum modulation.
Signed-off-by: Marcin Ciupak <marcin.s.ciupak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/pi433/rf69.c

@@ -117,7 +117,7 @@ enum modulation rf69_get_modulation(struct spi_device *spi)
 	switch (currentValue & MASK_DATAMODUL_MODULATION_TYPE >> 3) { // TODO improvement: change 3 to define
 	case DATAMODUL_MODULATION_TYPE_OOK: return OOK;
 	case DATAMODUL_MODULATION_TYPE_FSK: return FSK;
-	default:			    return undefined;
+	default:			    return UNDEF;
 	}
 }
 

drivers/staging/pi433/rf69_enum.h

@@ -28,7 +28,8 @@ enum mode {
 
 enum modulation {
 	OOK,
-	FSK
+	FSK,
+	UNDEF
 };
 
 enum mod_shaping {