I'm afraid that if you want the Homescreen to rotate to landscape orientation, you'll have to accept the rotating wallpaper. There's no way to separately control the wallpaper and homescreen rotation. The only control you have is to disable the homescreen rotation feature completely. To do this, go to Settings>Displat & Brightness>View>Display Zoom and tap on the Zoomed button, then tap the Set button at the top right. After the display resets, the app icons will be a little bigger and the homescreen won't rotate. Go back to Standard View if you want the screen to rotate again.