Boot: integrate MCUBoot with TF-M to act as a BL2 bootloader

Modifications in MCUBoot to be aligned with BL2 requirements in TF-M:
 -- OS dependency was removed, no need to copy any OS repo to build it
 -- CMSIS serial driver is used
 -- flash driver interface is aligned with original version
 -- S and NS images are handeled as a single binary blob
 -- automatic image concatenation and signing at build time
 -- authentication based on SHA256 and RSA-2048 digital signature
 -- mbedTLS library is used for cryptographic operation
 -- static analyser warnings fixed in some files

Change-Id: I54891762eac8d0df634e954ff19a9505b16f3028
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
diff --git a/bl2/ext/mcuboot/keys.c b/bl2/ext/mcuboot/keys.c
index 56b78df..7bad135 100644
--- a/bl2/ext/mcuboot/keys.c
+++ b/bl2/ext/mcuboot/keys.c
@@ -46,26 +46,11 @@
     0xc9, 0x02, 0x03, 0x01, 0x00, 0x01
 };
 const unsigned int root_pub_der_len = 270;
-#elif defined(MCUBOOT_SIGN_EC256)
-const unsigned char root_pub_der[] = {
-    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
-    0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
-    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03,
-    0x42, 0x00, 0x04, 0x2a, 0xcb, 0x40, 0x3c, 0xe8,
-    0xfe, 0xed, 0x5b, 0xa4, 0x49, 0x95, 0xa1, 0xa9,
-    0x1d, 0xae, 0xe8, 0xdb, 0xbe, 0x19, 0x37, 0xcd,
-    0x14, 0xfb, 0x2f, 0x24, 0x57, 0x37, 0xe5, 0x95,
-    0x39, 0x88, 0xd9, 0x94, 0xb9, 0xd6, 0x5a, 0xeb,
-    0xd7, 0xcd, 0xd5, 0x30, 0x8a, 0xd6, 0xfe, 0x48,
-    0xb2, 0x4a, 0x6a, 0x81, 0x0e, 0xe5, 0xf0, 0x7d,
-    0x8b, 0x68, 0x34, 0xcc, 0x3a, 0x6a, 0xfc, 0x53,
-    0x8e, 0xfa, 0xc1, };
-const unsigned int root_pub_der_len = 91;
 #else
 #error "No public key available for given signing algorithm."
 #endif
 
-#if defined(MCUBOOT_SIGN_RSA) || defined(MCUBOOT_SIGN_EC256)
+#if defined(MCUBOOT_SIGN_RSA)
 const struct bootutil_key bootutil_keys[] = {
     {
         .key = root_pub_der,