Bump SO version for libmbedcrypto

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/library/Makefile b/library/Makefile
index dc101d2..6fdc927 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -41,7 +41,7 @@
 
 SOEXT_TLS=so.13
 SOEXT_X509=so.1
-SOEXT_CRYPTO=so.6
+SOEXT_CRYPTO=so.7
 
 # Set AR_DASH= (empty string) to use an ar implementation that does not accept
 # the - prefix for command line options (e.g. llvm-ar)