Deprecated BF16 support in DepthConvert

* Removed BF16 validation tests for DepthConvert

* Revert back to using inline assembly to convert to/from BF16

* Resolves COMPMID-5800

Change-Id: I803b2ad19ead297417f780c97c5b724cca6b394c
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/8929
Reviewed-by: Jakub Sujak <jakub.sujak@arm.com>
Reviewed-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/SConstruct b/SConstruct
index 161b3f2..8603017 100644
--- a/SConstruct
+++ b/SConstruct
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright (c) 2016-2022 Arm Limited.
+# Copyright (c) 2016-2023 Arm Limited.
 #
 # SPDX-License-Identifier: MIT
 #
@@ -302,7 +302,7 @@
         if "disable_mmla_fp" not in env['custom_options']:
             env.Append(CPPDEFINES = ['ARM_COMPUTE_ENABLE_SVEF32MM'])
 
-    env.Append(CXXFLAGS = ['-march=armv8.2-a+fp16+bf16']) # explicitly enable fp16 extension otherwise __ARM_FEATURE_FP16_VECTOR_ARITHMETIC is undefined
+    env.Append(CXXFLAGS = ['-march=armv8.2-a+fp16']) # explicitly enable fp16 extension otherwise __ARM_FEATURE_FP16_VECTOR_ARITHMETIC is undefined
 
 else: # NONE "multi_isa" builds