mm: introduce update memory flags api

There are cases when attributes of mapped virtual memory need
to be updated. E.g. in case there is loadable library/module
code loaded to the l2 memory then memory needs to be read-write.
After the code is loaded and is ready to be executed then
attributes of mapped memory should be updated to
read-only/executable without loosing memory contents.

Signed-off-by: Jaroslaw Stelter <Jaroslaw.Stelter@intel.com>