qmod: error on EEPROM erase fail

repeating the EEPROM erase (byte write) in case of byte write failure
could lead in an infinite loop.
log the error an return error code instead.

Change-Id: Id6f3654d877ca772ba04237da91a6e86e3f441ec
diff --git a/firmware/libboard/qmod/source/board_qmod.c b/firmware/libboard/qmod/source/board_qmod.c
index acd090f..bdc08f9 100644
--- a/firmware/libboard/qmod/source/board_qmod.c
+++ b/firmware/libboard/qmod/source/board_qmod.c
@@ -113,9 +113,11 @@
 	/* write the EEPROM once */
 	for (i = 0; i < 256; i++) {
 		int rc = eeprom_write_byte(0x50, i, 0xff);
-		/* if the result was negative, repeat that write */
-		if (rc < 0)
-			i--;
+		if (rc < 0) {
+			TRACE_ERROR("Erasing EEPROM failed at byte %u: 0x%02x\n\r",
+				i, __eeprom_bin[i]);
+			return 1;
+		}
 	}
 
 	return 0;