boot: bootutil: Add caps for encryption

Add a capability query for the two encryption options.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/boot/bootutil/src/caps.c b/boot/bootutil/src/caps.c
index dc91849..c341f8b 100644
--- a/boot/bootutil/src/caps.c
+++ b/boot/bootutil/src/caps.c
@@ -35,6 +35,12 @@
 #else
         res |= BOOTUTIL_CAP_SWAP_UPGRADE;
 #endif
+#if defined(MCUBOOT_ENCRYPT_RSA)
+	res |= BOOTUTIL_CAP_ENC_RSA;
+#endif
+#if defined(MCUBOOT_ENCRYPT_KW)
+	res |= BOOTUTIL_CAP_ENC_KW;
+#endif
 
         return res;
 }