cmake: Introduce version and soversion variables

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 4f9da39..59e175b 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -208,13 +208,13 @@
     add_library(${mbedx509_target} SHARED ${src_x509})
     set_base_compile_options(${mbedx509_target})
     target_compile_options(${mbedx509_target} PRIVATE ${LIBS_C_FLAGS})
-    set_target_properties(${mbedx509_target} PROPERTIES VERSION 4.0.0 SOVERSION 8)
+    set_target_properties(${mbedx509_target} PROPERTIES VERSION ${MBEDTLS_VERSION} SOVERSION ${MBEDTLS_X509_SOVERSION})
     target_link_libraries(${mbedx509_target} PUBLIC ${libs} ${tfpsacrypto_target})
 
     add_library(${mbedtls_target} SHARED ${src_tls})
     set_base_compile_options(${mbedtls_target})
     target_compile_options(${mbedtls_target} PRIVATE ${LIBS_C_FLAGS})
-    set_target_properties(${mbedtls_target} PROPERTIES VERSION 4.0.0 SOVERSION 21)
+    set_target_properties(${mbedtls_target} PROPERTIES VERSION ${MBEDTLS_VERSION} SOVERSION ${MBEDTLS_TLS_SOVERSION})
     target_link_libraries(${mbedtls_target} PUBLIC ${libs} ${mbedx509_target})
 
     if(GEN_FILES)