remove needless ISA_DMA_THRESHOLD

Architectures don't need to define ISA_DMA_THRESHOLD anymore.

Signed-off-by: FUJITA Tomonori <[email protected]>
Acked-by: James Bottomley <[email protected]>
Acked-by: David Howells <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
20 files changed