boot/mynewt: remove redundant mbedtls flag and enable CTR

Now flag defining config file for MbedTLS is global
(see apache/mynewt-core#3394),
so we do not have to include the same flag in bootutil package.
This also enables MBEDTLS_CIPHER_MODE_CTR in boot_serial test
package, as it is used in unit tests and it is disabled by default.

Signed-off-by: Michal Gorecki <michal.gorecki@codecoup.pl>

Author: m-gorecki

boot/boot_serial/test/syscfg.yml

@@ -21,3 +21,6 @@
 syscfg.vals:
     # This is here to work around the $notnull syscfg restriction.
     BOOT_SERIAL_DETECT_PIN: 0
+
+syscfg.vals.BOOTUTIL_USE_MBED_TLS:
+    MBEDTLS_CIPHER_MODE_CTR: 1

boot/bootutil/pkg.yml

@@ -31,9 +31,6 @@ pkg.apis:
 pkg.cflags:
     - "-DMCUBOOT_MYNEWT=1"
 
-pkg.cflags.BOOTUTIL_USE_MBED_TLS:
-    - '-DMBEDTLS_USER_CONFIG_FILE="mbedtls/config_mynewt.h"'
-
 pkg.deps:
     - "@mcuboot/boot/mynewt/mcuboot_config"
     - "@apache-mynewt-core/hw/hal"

ci/mynewt_keys/enc_rsa/pkg.yml

@@ -20,6 +20,3 @@
 pkg.name: keys/enc_rsa
 pkg.author: "Apache Mynewt <dev@mynewt.apache.org>"
 pkg.homepage: "http://mynewt.apache.org/"
-
-pkg.cflags:
-    - '-DMBEDTLS_USER_CONFIG_FILE="mbedtls/config_mynewt.h"'