Merge enc/dec cipher contexts in ssl transforms

Store the raw encryption and decryption keys in transforms
to set them before each cipher operation. Add a config option
for this - MBEDTLS_SSL_TRANSFORM_OPTIMIZE_CIPHERS.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/scripts/config.pl b/scripts/config.pl
index b63dc77..5d2b28e 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -57,6 +57,7 @@
 #   MBEDTLS_AES_ONLY_ENCRYPT
 #   MBEDTLS_AES_SCA_COUNTERMEASURES
 #   MBEDTLS_CTR_DRBG_USE_128_BIT_KEY
+#   MBEDTLS_SSL_TRANSFORM_OPTIMIZE_CIPHERS
 #   and any symbol beginning _ALT
 #
 # The baremetal configuration excludes options that require a library or
@@ -140,6 +141,7 @@
 MBEDTLS_AES_ONLY_ENCRYPT
 MBEDTLS_AES_SCA_COUNTERMEASURES
 MBEDTLS_CTR_DRBG_USE_128_BIT_KEY
+MBEDTLS_SSL_TRANSFORM_OPTIMIZE_CIPHERS
 _ALT\s*$
 );