dmaengine: idxd: add support for readonly config mode

mainline inclusion
from mainline-v5.13
commit 8c66bbdc
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO


CVE: NA

Intel-SIG: commit 8c66bbdc dmaengine: idxd: add support for readonly config mode.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

--------------------------------

The read-only configuration mode is defined by the DSA spec as a mode of
the device WQ configuration. When GENCAP register bit 31 is set to 0,
the device is in RO mode and group configuration and some fields of the
workqueue configuration registers are read-only and reflect the fixed
configuration of the device. Add support for RO mode. The driver will
load the values from the registers directly setup all the internally
cached data structures based on the device configuration.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/161894438847.3202472.6317563824045432727.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>