!9276 Fix the bug of broadcasting the parameters in IGamma and LBeta

From: @peixu_ren
Reviewed-by: @zichun_ye,@sunnybeike
Signed-off-by: @sunnybeike

mindspore/nn/layer/math.py

@@ -666,9 +666,11 @@ class IGamma(Cell):
         domain_error = self.logicalor(self.less(x, 0), self.less(a, 0))
         use_igammac = self.logicaland(self.greater(x, 1), self.greater(x, a))
         ax = a * self.log(x) - x - self.lgamma(a)
-        boradcastto = P.BroadcastTo(self.shape(ax))
-        a = boradcastto(a)
+        para_shape = self.shape(ax)
+        boradcastto = P.BroadcastTo(para_shape)
+        if para_shape != ():
             x = boradcastto(x)
+            y = boradcastto(y)
         x_is_zero = self.equal(x, 0)
         if a_dtype == mstype.float64:
             log_maxfloat = self.log_maxfloat64
@@ -741,7 +743,9 @@ class LBeta(Cell):
         _check_input_dtype("input_x", x_dtype, [mstype.float16, mstype.float32], self.cls_name)
         _check_input_dtype("input_y", y_dtype, x_dtype, self.cls_name)
         x_plus_y = x + y
-        boradcastto = P.BroadcastTo(self.shape(x_plus_y))
+        para_shape = self.shape(x_plus_y)
+        boradcastto = P.BroadcastTo(para_shape)
+        if para_shape != ():
             x = boradcastto(x)
             y = boradcastto(y)
         comp_less = self.less(x, y)