update ios ad size and smart banner size

Use the adWidth and adHeight parameters instead of width and height for determining the size of the ad request to be consistent with the android version. Additionally, it utilizes the smart banner sizes 'kGADAdSizeSmartBannerPortrait ' and 'kGADAdSizeSmartBannerLandscape' for ios defined here:  https://developers.google.com/mobile-ads-sdk/docs/admob/ios/banner#smart_banners