remove codegen-nosub from q_8w (#6859)

Summary:

After #6781 the 8-bit linear shader can run on swiftshader.

Reviewed By: jorgep31415

Differential Revision: D65951046

Author: nathanaelsee

backends/vulkan/runtime/graph/ops/glsl/q_8w_linear.glsl

@@ -6,8 +6,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// codegen-nosub
-
 #version 450 core
 
 #define PRECISION ${PRECISION}