Update tee_ta_manager.c

Fix user heap corruption by usr_params

Avoids corruption of heap by usr_params, and vice versa, when 
stack_size+heap_size is a multiple of 1 MiB. usr_params was
previously unintentionally stored just outside the allocated
stack. If there is not enough padding between stack and heap,
usr_params will overwrite a part of the heap.
when the parameter phyical regin is 
    p->memref.buffer = 0x5F0000
    p->memref.size =       0x20000
the physical sections should be mapped is 5 and 6

so 
((((uint32_t) p->memref.buffer & SECTION_MASK) +
 		      p->memref.size) >> SECTION_SHIFT) + 1;
should also change to 
(((uint32_t) p->memref.buffer  +
 		      p->memref.size) >> SECTION_SHIFT) + 1;