hqd : Use proper type casts

    * Remove compilation errors
    * Use proper type casts

Change-Id: I1d44c2a2362a1fdd4d6e412ea816d4078e8355c9
:
diff --git a/liblight/lights.c b/liblight/lights.c
index 229777a..1aa0b58 100644
--- a/liblight/lights.c
+++ b/liblight/lights.c
@@ -84,7 +84,7 @@
     if (fd >= 0) {
         char buffer[20];
         int bytes = sprintf(buffer, "%d\n", value);
-        int amt = write(fd, buffer, bytes);
+        ssize_t amt = write(fd, buffer, (size_t)bytes);
         close(fd);
         return amt == -1 ? -errno : 0;
     } else {