rdma/siw: Add missing dependencies on LIBCRC32C and DMA_VIRT_OPS

If LIBCRC32C and DMA_VIRT_OPS are not enabled:

    drivers/infiniband/sw/siw/siw_main.o: In function `siw_newlink':
    siw_main.c:(.text+0x35c): undefined reference to `dma_virt_ops'
    drivers/infiniband/sw/siw/siw_qp_rx.o: In function `siw_csum_update':
    siw_qp_rx.c:(.text+0x16): undefined reference to `crc32c'

Fix the first issue by adding a select of DMA_VIRT_OPS.  Fix the second
issue by replacing the unneeded dependency on CRYPTO_CRC32 by a dependency
on LIBCRC32C.

Reported-by: noreply@ellerman.id.au (first issue)
Fixes: c0cf5bdd

 ("rdma/siw: addition to kernel build environment")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>