merge tee_pager*.c and tee_pager*.h files

* Merges tee_pager_unpg.c and tee_pager.c into tee_pager.c
* Merges tee_pager_unpg.h and tee_pager.h into tee_pager.h

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
arm32: add thread_init_per_cpu()

Adds a thread_init_per_cpu() function that should be called instead of
thread_init_handlers() by the secondary CPUs. The primary CPU should first
call thread_init_handlers() and then thread_init_per_cpu().

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
arm32: split and enhance core_init_mmu()

* Splits core_init_mmu() into two functions, core_init_mmu_tables() called
  by primary CPU to create the translation tables and core_init_mmu_regs()
  called by each CPU to initialize MMU register settings.
* Adds option to map certain areas in a level 2 translation table instead
  of only level 1 mapping. Allocation of the level 2 translation tables
  is implemented in platform specific code, a weak function is provided
  in case the platform doesn't implement/need the function.
* Adds L2 translation table for STM and Vexpress.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org> (STM platform)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (QEMU virt platform)