New naming convention for internal macros

This is the first patch introducing the new naming convention
for the UST tracer. To prevent namespace pollution, _ust_ prefix
is added to internal macros which are visible in the global header.

For this patch, only the container_of macro is renamed and the
redundant definition in kcompat/simple.h is removed.

Signed-off-by: David Goulet <david.goulet@polymtl.ca>
Acked-by: Nils Carlson <nils.carlson@ericsson.com>