RTL: Bring in updates from mor1kx
SystemSW: Unify mutex API
SystemSW: Disable low level trace for mp_simple
SystemSW: Change interrupt fptr in mp_simple
SystemSW: Change compile flags

At the moment, the newlib toolchain needs to be compiled with
multicore support or without. Remove -mmulticore temporarily, it may
become a multilib thing in future.
SystemSW: Change NoC classes in mp library
SystemSW: Fix incorrect memory allocation