libcamera: Use helper variable template for type traits

C++17 introduces helper variable templates for type traits, allowing
shortening std::is_foo<T>::value to std::is_foo_v<T>. Use them through
the code base.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

include/libcamera/object.h

@@ -32,7 +32,7 @@ public:
 	void postMessage(std::unique_ptr<Message> msg);
 
 	template<typename T, typename R, typename... FuncArgs, typename... Args,
-		 typename std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
+		 typename std::enable_if_t<std::is_base_of_v<Object, T>> * = nullptr>
 	R invokeMethod(R (T::*func)(FuncArgs...), ConnectionType type,
 		       Args... args)
 	{