cnss: Update prealloc memory table

The memory size of a slot in the prealloc table should be order of 2,
otherwise some memory will be wasted since kernel only allocates
contiguous physical memory in pages by order of 2.

Change-Id: I762ad490d300f8b622a3ed1f9ccbe2af2d926c49
Signed-off-by: Yue Ma <yuem@codeaurora.org>