[stp] Fix incorrectly disambiguated errors

The three nominally-disambiguated ENOTSUP errors accidentally all used
the same error disambiguator, rendering them identical.  Fix by
changing all three values.  We avoid reusing the 0x01 disambiguator
value, since that remains ambiguous in older binaries.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/net/stp.c

 /* Disambiguate the various error causes */
 #define ENOTSUP_PROTOCOL __einfo_error ( EINFO_ENOTSUP_PROTOCOL )
 #define EINFO_ENOTSUP_PROTOCOL					\
-	__einfo_uniqify ( EINFO_ENOTSUP, 0x01,			\
+	__einfo_uniqify ( EINFO_ENOTSUP, 0x02,			\
 			  "Non-STP packet received" )
 #define ENOTSUP_VERSION __einfo_error ( EINFO_ENOTSUP_VERSION )
 #define EINFO_ENOTSUP_VERSION					\
-	__einfo_uniqify ( EINFO_ENOTSUP, 0x01,			\
+	__einfo_uniqify ( EINFO_ENOTSUP, 0x03,			\
 			  "Legacy STP packet received" )
 #define ENOTSUP_TYPE __einfo_error ( EINFO_ENOTSUP_TYPE )
 #define EINFO_ENOTSUP_TYPE					\
-	__einfo_uniqify ( EINFO_ENOTSUP, 0x01,			\
+	__einfo_uniqify ( EINFO_ENOTSUP, 0x04,			\
 			  "Non-RSTP packet received" )
 
 /**