drm/xe: Rely on kmalloc/kzalloc log message

Those messages are unnecessary because a generic message is already
produced in case of allocation failure. Besides, this also removes a
misuse of the XE_IOCTL_DBG macro.

Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>