The latest QE chip may have more Serial Number(SNUM)s of thread to use. We
will get the number of SNUMs from device tree by reading the new property
"fsl,qe-num-snums", and set 28 as the default number of SNUMs so that it is
compatible with the old QE chips' device trees which don't have this new
property. The macro QE_NUM_OF_SNUM is defined as the maximum number in QE
snum table which is 256.

Also we update the snum_init[] array with 18 more new SNUMs which are
confirmed to be useful on new chip.

Signed-off-by: Haiying Wang <Haiying.Wang@freescale.com>
Acked-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>