Remove unneeded symbols from python layers.

The input_spec should be exported via tf_export already in keras.

PiperOrigin-RevId: 302504252
Change-Id: I73aa4cc9d8adadb23b1f5aa455ddfd1008e2080e

tensorflow/python/BUILD

@@ -7105,7 +7105,6 @@ py_library(
     srcs_version = "PY2AND3",
     deps = [
         ":layers_base",
-        "//tensorflow/python/keras/engine:input_spec",
         "//tensorflow/python/keras/legacy_tf_layers:convolutional",
         "//tensorflow/python/keras/legacy_tf_layers:core",
         "//tensorflow/python/keras/legacy_tf_layers:normalization",

tensorflow/python/layers/layers.py

@@ -24,7 +24,6 @@ from __future__ import print_function
 
 # Base objects.
 from tensorflow.python.layers.base import Layer
-from tensorflow.python.keras.engine.input_spec import InputSpec
 
 # Core layers.
 from tensorflow.python.layers.core import Dense