For block span more than 1 section, when allocate it from
a free block, we need allocate the remain buffers within
the block, and then continue alloc the rest of needed
size buffer.

Here also make sure this free block is moved from free
list to used list, and add it to block_list which may
be used for power gating disabling later.
Signed-off-by: NJie Yang <yang.jie@intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>