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
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:a001114eaa6e025ec1633b19b6bdbd8dd45b0974)
Merged-In: Idb45decc64ad90da72a837a3fd7f19b3d2c182b2
Change-Id: Idb45decc64ad90da72a837a3fd7f19b3d2c182b2