Change get_core_pos() to read mpidr itself

Changes get_core_pos() to read mpidr itself instead of taking it
as a parameter. Secure monitor is changed to use get_core_pos()
when the index of the CPU is needed.
Always include debug symbols
Add STATIC_ASSERT
mmu_init use MMU_L1_NUM_ENTRIES

Uses MMU_L1_NUM_ENTRIES in mmu_init instead of magic number.