fix(mge/functional): reshape bias to (1, out_features) in linear

GitOrigin-RevId: a15880b7fc8917e36c5882ab09e8ce3f2c7b2727

python_module/megengine/functional/nn.py

@@ -44,7 +44,7 @@ def linear(inp: Tensor, weight: Tensor, bias: Optional[Tensor] = None) -> Tensor
     ret = mgb.opr.matrix_mul(inp, weight, transposeB=True)
     ret = ret.reshape(orig_shape[:-1], weight.shape[0])
     if bias is not None:
-        ret += bias
+        ret += bias.reshape(1, bias.shape[0])
     return ret