bionic-amd64-tf-m-build: Remove unused ArmClang variables

Related for older ArmClang versions (pre-UBL) which were removed and no
longer supported.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I300282231ffa521e6674675eaf35aefb6e1da071
diff --git a/bionic-amd64-tf-m-build/Dockerfile b/bionic-amd64-tf-m-build/Dockerfile
index 4948c8c..f0bfd14 100644
--- a/bionic-amd64-tf-m-build/Dockerfile
+++ b/bionic-amd64-tf-m-build/Dockerfile
@@ -16,10 +16,6 @@
 ENV GCC_10_3_PATH=${GCC_10_3_DIR}/bin
 ENV GCC_11_2_DIR=${COMPILER_DIR}/gcc-11-2
 ENV GCC_11_2_PATH=${GCC_11_2_DIR}/bin
-ENV ARMCLANG_6_13_DIR=${COMPILER_DIR}/armclang-6-13
-ENV ARMCLANG_6_13_PATH=${ARMCLANG_6_13_DIR}/bin
-ENV ARMCLANG_6_18_DIR=${COMPILER_DIR}/armclang-6-18
-ENV ARMCLANG_6_18_PATH=${ARMCLANG_6_18_DIR}/bin
 ENV ARMCLANG_6_20_DIR=${COMPILER_DIR}/armclang-6-20
 ENV ARMCLANG_6_20_PATH=${ARMCLANG_6_20_DIR}/bin
 ENV ARMCLANG_6_21_DIR=${COMPILER_DIR}/armclang-6-21
diff --git a/bionic-amd64-tf-m-build/tf-environment.install b/bionic-amd64-tf-m-build/tf-environment.install
index 021b837..afe5244 100755
--- a/bionic-amd64-tf-m-build/tf-environment.install
+++ b/bionic-amd64-tf-m-build/tf-environment.install
@@ -10,4 +10,3 @@
 env | grep PATH >> /etc/environment
 env | grep GCC_7_3_1_PATH >> /etc/environment
 env | grep GCC_10_3_PATH >> /etc/environment
-env | grep ARMCLANG_6_13_PATH >> /etc/environment