ARM: dts: mxs: Add spi alias

After providing spi alias, we can get the following message during probe:

m25p80 spi1.0: sst25vf016b (2048 Kbytes)

,which looks better than the original one:

m25p80 spi32766.0: sst25vf016b (2048 Kbytes)

While at it, keep the alias entries in alphabetical order.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>