Update eva.py (#2058)

* Update eva.py

When argument class token = False, self.cls_token = None.

Prevents error from attempting trunc_normal_ on None:
AttributeError: 'NoneType' object has no attribute 'uniform_'

* Update eva.py

fix

timm/models/eva.py

@@ -479,7 +479,8 @@ class Eva(nn.Module):
         self.apply(self._init_weights)
         if self.pos_embed is not None:
             trunc_normal_(self.pos_embed, std=.02)
-        trunc_normal_(self.cls_token, std=.02)
+        if self.cls_token is not None:
+            trunc_normal_(self.cls_token, std=.02)
 
         self.fix_init_weight()
         if isinstance(self.head, nn.Linear):