drm/xe: Add fault injection for xe_oa_alloc_regs

Add fault injection for xe_oa_alloc_regs to allow it to fail while
executing xe_oa_add_config_ioctl().
This need to be added as it cannot be reached by injecting error through
IOCTL arguments.

Signed-off-by: Nakshtra Goyal <nakshtra.goyal@intel.com>
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://lore.kernel.org/r/20250227102339.2859726-1-nakshtra.goyal@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

drivers/gpu/drm/xe/xe_oa.c

@@ -2221,6 +2221,7 @@ xe_oa_alloc_regs(struct xe_oa *oa, bool (*is_valid)(struct xe_oa *oa, u32 addr),
 	kfree(oa_regs);
 	return ERR_PTR(err);
 }
+ALLOW_ERROR_INJECTION(xe_oa_alloc_regs, ERRNO);
 
 static ssize_t show_dynamic_id(struct kobject *kobj,
 			       struct kobj_attribute *attr,