lmb: replace the lmb_alloc() and lmb_alloc_base() API's

lmb: replace the lmb_alloc() and lmb_alloc_base() API's

There currently are two API's for requesting memory from the LMB
module, lmb_alloc() and lmb_alloc_base(). The function which does the
actual allocation is the same. Use the earlier introduced API
lmb_alloc_mem() for both types of allocation requests.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>