pmem: ensure SMI correctness

Due to hardware constraints, the SMI should not be mapped
in the kernel space when not in use. Unmap the SMI from
the kernel address space when the last allocation is freed.
Vote for bus bandwidth as well while the SMI is allocated.

CRs-Fixed: 281723
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
3 files changed