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

In the Linux kernel, the following vulnerability has been resolved:

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)

(cherry picked from commit e057b2d2b8d815df3858a87dffafa2af37e5945b)