dtc has new checks for SPI buses. Fix the warnings in node names.

arch/arm/boot/dts/bcm53340-ubnt-unifi-switch8.dtb: Warning (spi_bus_bridge): /axi@18000000/qspi@27200: node name for SPI buses should be 'spi'
arch/arm/boot/dts/bcm958525er.dtb: Warning (spi_bus_bridge): /axi/qspi@27200: node name for SPI buses should be 'spi'
arch/arm/boot/dts/bcm958525xmc.dtb: Warning (spi_bus_bridge): /axi/qspi@27200: node name for SPI buses should be 'spi'
arch/arm/boot/dts/bcm958622hr.dtb: Warning (spi_bus_bridge): /axi/qspi@27200: node name for SPI buses should be 'spi'
arch/arm/boot/dts/bcm958625hr.dtb: Warning (spi_bus_bridge): /axi/qspi@27200: node name for SPI buses should be 'spi'
arch/arm/boot/dts/bcm988312hr.dtb: Warning (spi_bus_bridge): /axi/qspi@27200: node name for SPI buses should be 'spi'

Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Jon Mason <jonmason@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>