QU8 remove prototypes for microkernels that do not exist.

PiperOrigin-RevId: 362108027
diff --git a/src/xnnpack/gemm.h b/src/xnnpack/gemm.h
index be2fcf9..87a1ed9 100644
--- a/src/xnnpack/gemm.h
+++ b/src/xnnpack/gemm.h
@@ -500,18 +500,11 @@
 DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_4x8__neon)
 DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_8x8__neon)
 
-DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_4x8__aarch32_neon)
-
-DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_8x8__aarch64_neon)
-
 DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_2x4c8__sse2)
 DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_4x4c2__sse2)
 
 DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_2x2__scalar)
 
-DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_8x8c4__scalar)
-DECLARE_QU8_GEMM_MINMAX_UKERNEL_FUNCTION(xnn_qu8_gemm_minmax_ukernel_12x4c4__scalar)
-
 #define DECLARE_QS8_GEMM_MINMAX_UKERNEL_FUNCTION(fn_name) \
   XNN_INTERNAL void fn_name(                              \
       size_t mr,                                          \