Don't change anything if multi_crop is false.

The legacy WallpaperDataParser (without multi-crop) was inadvertently
loading new attributes ("totalCropLeft, totalCropRight, ...") instead of
old ones ("cropLeft, cropRight, ...") even when the flag was false.

Flag: NA, fixes an issue outside flag
Bug: 329259443
Test: manually spotted the issue
Change-Id: Idb45decc64ad90da72a837a3fd7f19b3d2c182b2