staging: zsmalloc: Ensure handle is never 0 on success
zsmalloc encodes a handle using the pfn and an object
index. On hardware platforms with physical memory starting
at 0x0 the pfn can be 0. This causes the encoded handle to be
0 and is incorrectly interpreted as an allocation failure.
This issue affects all current and future SoCs with physical
memory starting at 0x0. All MSM8974 SoCs which includes
Google Nexus 5 devices are affected.
To prevent this false error we ensure that the encoded handle
will not be 0 when allocation succeeds.