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

arch/arm64/boot/dts/amd/amd-overdrive.dtb: Warning (spi_bus_bridge): /smb/ssp@e1030000: node name for SPI buses should be 'spi'
arch/arm64/boot/dts/amd/amd-overdrive-rev-b0.dtb: Warning (spi_bus_bridge): /smb/ssp@e1030000: node name for SPI buses should be 'spi'
arch/arm64/boot/dts/amd/amd-overdrive-rev-b1.dtb: Warning (spi_bus_bridge): /smb/ssp@e1030000: node name for SPI buses should be 'spi'

Cc: Brijesh Singh <brijeshkumar.singh@amd.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>