dtc has new checks for SPI buses. Fix the warnings in node names and
unit-addresses.

There's over 100 warnings for FSL boards, a few examples:

arch/arm/boot/dts/imx28-duckbill-2-spi.dtb: Warning (spi_bus_bridge): /apb@80000000/apbh@80000000/ssp@80014000: node name for SPI buses should be 'spi'
arch/arm/boot/dts/imx53-ppd.dtb: Warning (spi_bus_bridge): /soc/aips@50000000/spba@50000000/ecspi@50010000: node name for SPI buses should be 'spi'
arch/arm/boot/dts/imx6dl-colibri-eval-v3.dtb: Warning (spi_bus_reg): /soc/aips-bus@2000000/spba-bus@2000000/spi@2014000/mcp251x@1: SPI bus unit address format error, expected "0"

Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Li Yang <leoyang.li@nxp.com>
Cc: Stefan Agner <stefan@agner.ch>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>