radeon: fix cs buffer realloc padding

We always realloc at least 0x1000 dwords (page on most system)
when growing the cs buffer this is to avoid having to realloc
at each cs_begin.

libdrm/radeon/radeon_cs_gem.c

@@ -225,9 +225,8 @@ static int cs_gem_begin(struct radeon_cs *cs,
 
     if (cs->cdw + ndw > cs->ndw) {
         uint32_t tmp, *ptr;
-	int num = (ndw > 0x3FF) ? ndw : 0x3FF;
 
-        tmp = (cs->ndw + 1 + num) & (~num);
+        tmp = (cs->ndw + 1 + 0x3FF) & (~0x3FF);
         ptr = (uint32_t*)realloc(cs->packets, 4 * tmp);
         if (ptr == NULL) {
             return -ENOMEM;