rdma: Fix for ineffective check in add_filter()

With 'name' field defined as array in struct filters, it will always
contain a value irrespective of whether a name was assigned or not.

Fix this by turning the field into a const char pointer.

Fixes: 1174be72d1 ("rdma: Add filtering infrastructure")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

rdma/rdma.h

@@ -34,7 +34,7 @@
 
 #define MAX_NUMBER_OF_FILTERS 64
 struct filters {
-	char name[32];
+	const char *name;
 	bool is_number;
 };