Clarify GCC version requirement

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
diff --git a/tests/scripts/components-platform.sh b/tests/scripts/components-platform.sh
index 42f41f5..8a94d09 100644
--- a/tests/scripts/components-platform.sh
+++ b/tests/scripts/components-platform.sh
@@ -449,6 +449,7 @@
 }
 
 support_test_aarch64_linux_gnu_gcc () {
+    # Minimum version of GCC for MBEDTLS_AESCE_C is 6.0
     [ "$(gcc_version "${AARCH64_LINUX_GNU_GCC_PREFIX}gcc")" -ge 6 ] && can_run_aarch64_linux_gnu
 }