Enable march=armv8.6-a in non multi-isa builds

* scons arch=armv8.6-a translates to -march=armv8.6-a
* scons arch=armv8.6-a-sve translates to -march=armv8.6-a+sve
* scons arch=armv8.6-a-sve2 translates to -march=armv8.6-a+sve2
* Resolves COMPMID-5408

Change-Id: I0901e1de864d00109759509af7cc2b5c9ae1cd75
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7943
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/filedefs.json b/filedefs.json
index 76dccff..3422eeb 100644
--- a/filedefs.json
+++ b/filedefs.json
@@ -23,7 +23,8 @@
             },
             "armv8.6-a": {
                 "cxxflags": ["-march=armv8.6-a+fp16"],
-                "cppdefines": ["ARM_COMPUTE_ENABLE_FP16"]
+                "cppdefines": ["ARM_COMPUTE_ENABLE_FP16", "ARM_COMPUTE_ENABLE_BF16",
+                               "ARM_COMPUTE_ENABLE_I8MM"]
             },
             "armv8.6-a-sve": {
                 "cxxflags": ["-march=armv8.6-a+sve+fp16+dotprod"],
@@ -37,4 +38,4 @@
             }
         }
     }
-}
\ No newline at end of file
+}