lmb: make LMB memory map persistent and global

lmb: make LMB memory map persistent and global

The current LMB API's for allocating and reserving memory use a
per-caller based memory view. Memory allocated by a caller can then be
overwritten by another caller. Make these allocations and reservations
persistent using the alloced list data structure.

Two alloced lists are declared -- one for the available(free) memory,
and one for the used memory. Once full, the list can then be extended
at runtime.

[sjg: Use a stack to store pointer of lmb struct when running lmb tests]

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
[sjg: Optimise the logic to add a region in lmb_add_region_flags()]