Cocoa: Fix AirPlay causing harmless init error

Emitting an error for one specific type of failure in retrieving the
correct name for a display is not very useful, especially when
initialization is otherwise unaffected.

There should be a path for information like that but this isn't it.

Fixes #1791

src/cocoa_monitor.m

@@ -98,11 +98,7 @@ static char* getMonitorName(CGDirectDisplayID displayID, NSScreen* screen)
     IOObjectRelease(it);
 
     if (!service)
-    {
-        _glfwInputError(GLFW_PLATFORM_ERROR,
-                        "Cocoa: Failed to find service port for display");
         return _glfw_strdup("Display");
-    }
 
     CFDictionaryRef names =
         CFDictionaryGetValue(info, CFSTR(kDisplayProductName));