mm: cma: align to physical address, not CMA region position

mm: cma: align to physical address, not CMA region position

The alignment in cma_alloc() was done w.r.t. the bitmap.  This is a
problem when, for example:

- a device requires 16M (order 12) alignment
- the CMA region is not 16 M aligned

In such a case, can result with the CMA region starting at, say,
0x2f800000 but any allocation you make from there will be aligned from
there.  Requesting an allocation of 32 M with 16 M alignment will result
in an allocation from 0x2f800000 to 0x31800000, which doesn't work very
well if your strange device requires 16M alignment.

Change to use bitmap_find_next_zero_area_off() to account for the
difference in alignment at reserve-time and alloc-time.

Signed-off-by: Gregory Fong <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kukjin Kim <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Laura Abbott <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>