Notification : Fix app info long-press

Addresses http://code.google.com/p/cyanogenmod/issues/detail?id=7060

Change-Id: I45c0e1b73c08ceffef02db244b947bfcedf3b20a
Initialize pointer members to NULL to avoid illegal reference

mBitmap and mTexture is not initialized to NULL which causes
illegal address access when it fails to be created from
oversized bitmap.
Cherry-picked from AOSP: https://android-review.googlesource.com/#/c/79320/

Change-Id: Iea54bec8788bc5f3a10040fdb43f416c0d41a14c