cam: options: Slit OptionsParser::usage() in two functions

To prepare for code reuse, split the printing of options out of
OptionsParser::usage() to a separate function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/cam/options.h

@@ -95,6 +95,8 @@ public:
 	void usage();
 
 private:
+	void usageOptions(const std::list<Option> &options, unsigned int indent);
+
 	std::list<Option> options_;
 	std::map<unsigned int, Option *> optionsMap_;
 };