ospfd: Changed TE instance check to remove -Wtype-limits warning

Since LEGAL_TE_INSTANCE_RANGE() was being passed an unsigned int, a warning
was being thrown due to the compare against >= 0.  Since this macro was used
only in one place, I removed the macro for an explict compare against a
constant for the MAX.

Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
diff --git a/ospfd/ospf_te.h b/ospfd/ospf_te.h
index e8511cd..863d8ba 100644
--- a/ospfd/ospf_te.h
+++ b/ospfd/ospf_te.h
@@ -41,7 +41,7 @@
  *
  */
 
-#define	LEGAL_TE_INSTANCE_RANGE(i)	(0 <= (i) && (i) <= 0xffff)
+#define	MAX_LEGAL_TE_INSTANCE_NUM (0xffff)
 
 /*
  *        24       16        8        0