genalloc:support memory-allocation with bytes-alignment to genalloc

Bytes alignment is required to manage some special RAM,
so add gen_pool_first_fit_align to genalloc,
meanwhile add gen_pool_alloc_algo to pass algo in case user
layer using more than one algo, and pass data to
gen_pool_first_fit_align(modify gen_pool_alloc as a wrapper)

Signed-off-by: Zhao Qiang <qiang.zhao@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>