soc: qcom: mem-offline: Add a snapshot of the mem-offline driver

This is a snapshot of the mem-offline driver as of msm-4.19
commit ef9b421ba16b ("sched: walt: Improve the scheduler").

Change-Id: I81be12ce85033d5d5ab6be8b10aa76a2685d5720
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>