boot: zephyr: add ECIES-P256 configuration

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/zephyr/keys.c b/boot/zephyr/keys.c
index ee61c7d..afc0ea6 100644
--- a/boot/zephyr/keys.c
+++ b/boot/zephyr/keys.c
@@ -176,6 +176,26 @@
     .key = enc_priv_key,
     .len = &enc_priv_key_len,
 };
+#elif defined(MCUBOOT_ENCRYPT_EC256)
+unsigned char enc_priv_key[] = {
+  0x30, 0x81, 0x87, 0x02, 0x01, 0x00, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
+  0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a, 0x86, 0x48, 0xce, 0x3d,
+  0x03, 0x01, 0x07, 0x04, 0x6d, 0x30, 0x6b, 0x02, 0x01, 0x01, 0x04, 0x20,
+  0xf6, 0x1e, 0x51, 0x9d, 0xf8, 0xfa, 0xdd, 0xa1, 0xb7, 0xd9, 0xa9, 0x64,
+  0x64, 0x3b, 0x54, 0xd0, 0x3d, 0xd0, 0x1f, 0xe5, 0x78, 0xd9, 0x17, 0x98,
+  0xa5, 0x28, 0xca, 0xcc, 0x6b, 0x67, 0x9e, 0x06, 0xa1, 0x44, 0x03, 0x42,
+  0x00, 0x04, 0x8a, 0x44, 0x73, 0x00, 0x94, 0xc9, 0x80, 0x27, 0x31, 0x0d,
+  0x23, 0x36, 0x6b, 0xe9, 0x69, 0x9f, 0xcb, 0xc5, 0x7c, 0xc8, 0x44, 0x1a,
+  0x93, 0xe6, 0xee, 0x7d, 0x86, 0xa6, 0xae, 0x5e, 0x93, 0x72, 0x74, 0xd9,
+  0xe1, 0x5a, 0x1c, 0x9b, 0x65, 0x1a, 0x2b, 0x61, 0x41, 0x28, 0x02, 0x73,
+  0x84, 0x12, 0x97, 0x3a, 0x2d, 0xa2, 0xa0, 0x67, 0x77, 0x02, 0xda, 0x67,
+  0x1a, 0x4b, 0xdd, 0xd7, 0x71, 0xcc,
+};
+static unsigned int enc_priv_key_len = 138;
+const struct bootutil_key bootutil_enc_key = {
+    .key = enc_priv_key,
+    .len = &enc_priv_key_len,
+};
 #elif defined(MCUBOOT_ENCRYPT_KW)
 #error "Encrypted images with AES-KW is not implemented yet."
 #endif