dmaengine: idxd: check GENCAP config support for gencfg register

mainline inclusion
from mainline-v5.16
commit 79c4c3db
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO


CVE: NA

Intel-SIG: commit 79c4c3db dmaengine: idxd: check GENCAP config support for gencfg register.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

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

DSA spec 1.2 has moved the GENCFG register under the GENCAP configuration
support with respect to writability. Add check in driver before writing to
GENCFG register.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163406171896.1303830.11217958011385656998.stgit@djiang5-desk3.ch.intel.com


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