lib: fix seperator in snprintf_error_data

When multiple error flags are set, snprintf_error_data created a comma
seperated textual presentation of it. Commit ef853f5553 ("added return value
check of snprintf to prevent possible buffer overflows detected by CodeQL")
removed the increment of count, so the delimiter is no longer added. Fix this
by incrementing count again.

Fixes: Commit ef853f5553 ("added return value check of snprintf to prevent possible buffer overflows detected by CodeQL")
Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>

lib.c

@@ -582,6 +582,7 @@ static int snprintf_error_data(char *buf, size_t len, uint8_t err,
 				return n;
 			}
 			n += tmp_n;
+			count++;
 		}
 	}