Add support for building p256-m alongside Mbed TLS with CMake.
Also check if p256-m is enabled in the config before including the contents of p256-m.c

Signed-off-by: Aditya Deshpande <aditya.deshpande@arm.com>
diff --git a/3rdparty/p256-m/CMakeLists.txt b/3rdparty/p256-m/CMakeLists.txt
new file mode 100644
index 0000000..64d0d0f
--- /dev/null
+++ b/3rdparty/p256-m/CMakeLists.txt
@@ -0,0 +1,25 @@
+add_library(p256m
+    p256-m_driver_entrypoints.c
+    p256-m/p256-m.c)
+
+target_include_directories(p256m
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/p256-m>
+         $<BUILD_INTERFACE:${MBEDTLS_DIR}/include>
+         $<INSTALL_INTERFACE:include>
+  PRIVATE ${MBEDTLS_DIR}/library/)
+
+if(INSTALL_MBEDTLS_HEADERS)
+
+  install(DIRECTORY :${CMAKE_CURRENT_SOURCE_DIR}
+    DESTINATION include
+    FILE_PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+    DIRECTORY_PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE
+    FILES_MATCHING PATTERN "*.h")
+
+endif(INSTALL_MBEDTLS_HEADERS)
+
+install(TARGETS p256m
+EXPORT MbedTLSTargets
+DESTINATION ${CMAKE_INSTALL_LIBDIR}
+PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ)
\ No newline at end of file