dmaengine: idxd: deprecate token sysfs attributes for read buffers

dmaengine: idxd: deprecate token sysfs attributes for read buffers

The following sysfs attributes will be obsolete due to the name change of
tokens to read buffers:
max_tokens
token_limit
group/tokens_allowed
group/tokens_reserved
group/use_token_limit

Create new entries and have old entry print warning of deprecation.

New attributes to replace the token ones:
max_read_buffers
read_buffer_limit
group/read_buffers_allowed
group/read_buffers_reserved
group/use_read_buffer_limit

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163951339488.2988321.2424012059911316373.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>