The structure of the message is static so we don't have
to use and cast the buffer. We can also drop extra_write_index
variable as this information can be extracted directly
from the message header
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>