[LMB]: Fix bug in __lmb_alloc_base().

We need to check lmb_add_region() for errors, it can run out
of regions etc.

Also, the size needs to be padded to the given alignment
or else the lmb.reserved regions don't get expanded and
instead we get tons of holes and eventually run out of
regions prematurely.

Signed-off-by: David S. Miller <davem@davemloft.net>