net: mvpp2: adjust the allocation/free of BM pools for PPv2.2

net: mvpp2: adjust the allocation/free of BM pools for PPv2.2

This commit adjusts the allocation and freeing of BM pools to support
PPv2.2. This involves:

- Checking that the number of buffer pointers is a multiple of 16, as
  required by the hardware.

- Adjusting the size of the DMA coherent area allocated for buffer
  pointers. Indeed, PPv2.2 needs space for 2 pointers of 64-bits per
  buffer, as opposed to 2 pointers of 32-bits per buffer in
  PPv2.1. The size in bytes is now stored in a new field of the
  mvpp2_bm_pool structure.

- On PPv2.2, getting the physical and virtual address of each buffer
  requires reading the MVPP2_BM_ADDR_HIGH_ALLOC to get the high order
  bits of those addresses. A new utility function
  mvpp2_bm_bufs_get_addrs() is introduced to handle this.

- On PPv2.2, releasing a buffer requires writing the high order 32 bits
  of the physical address to MVPP2_BM_PHY_VIRT_HIGH_RLS_REG. We no
  longer need to write the virtual address to MVPP2_BM_VIRT_RLS_REG.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>