msm: smem: Rename smem_alloc2_to_proc() to smem_alloc()

smem_alloc2_to_proc() is the preferred function for allocating SMEM items,
but its name is quite verbose with little added benefit to clients.  Rename
smem_alloc2_to_proc() to smem_alloc() as smem_alloc() succinctly describes
the purpose of the function.

Change-Id: I70519f6b237368f23ef1af2df4ba1c83dd774d20
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>