drm/xe/oa: Limit num_syncs to prevent oversized allocations

drm/xe/oa: Limit num_syncs to prevent oversized allocations

The OA open parameters did not validate num_syncs, allowing
userspace to pass arbitrarily large values, potentially
leading to excessive allocations.

Add check to ensure that num_syncs does not exceed DRM_XE_MAX_SYNCS,
returning -EINVAL when the limit is violated.

v2: use XE_IOCTL_DBG() and drop duplicated check. (Ashutosh)

Fixes: c8507a25cebd ("drm/xe/oa/uapi: Define and parse OA sync properties")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251205234715.2476561-6-shuicheng.lin@intel.com