ipa: ipa_interface: Declare ipaCreate() in libcamera namespace

The ipaCreate() function is the entry point to IPA modules. It is
declared in ipa_interface.h, and defined by each module. As the function
is defined with extern "C" linkage, the namespace in which it is
contained is not very relevant from a caller's point of view. For the
IPA module implementer, however, defining the function in the libcamera
namespace avoids adding an explicit libcamera:: prefix to the symbols
used by the function. This is why all IPA modules define their
ipaCreate() entry point in the libcamera namespace.

The ipa_interface.h file, however, declares the function in the global
namespace. This doesn't cause any issue at runtime, but will cause a
missing declaration warning when we enable them. To prepare for that,
move the function declaration to the libcamera namespace.

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

include/libcamera/ipa/ipa_interface.h

@@ -33,8 +33,8 @@ public:
 	virtual ~IPAInterface() = default;
 };
 
-} /* namespace libcamera */
-
 extern "C" {
 libcamera::IPAInterface *ipaCreate();
 }
+
+} /* namespace libcamera */