Added comments - mm.*, lpae.*, smp.h. 

Added comments - mm.h, mm.c, lpae.h, lpae.c and smp.h
Fixed Feature:
 lpae.c - TTBL_L1_OUTADDR_MAS 0x000000FFEC000000ULL -> 0x000000FFC0000000ULL
  Reason : Wrong masking address. ref - ARM Architecture Referene Manual.