arm64: dts: broadcom: Fix I2C and SPI bus warnings

dtc has new checks for I2C and SPI buses. Fix the warnings in node names
and unit-addresses.

arch/arm64/boot/dts/broadcom/stingray/bcm958742k.dtb: Warning (i2c_bus_reg): /hsls/i2c@e0000/pcf8574@20: I2C bus unit address format error, expected "27"
arch/arm64/boot/dts/broadcom/stingray/bcm958742t.dtb: Warning (i2c_bus_reg): /hsls/i2c@e0000/pcf8574@20: I2C bus unit address format error, expected "27"
arch/arm64/boot/dts/broadcom/stingray/bcm958742k.dtb: Warning (spi_bus_bridge): /hsls/ssp@180000: node name for SPI buses should be 'spi'
arch/arm64/boot/dts/broadcom/stingray/bcm958742k.dtb: Warning (spi_bus_bridge): /hsls/ssp@190000: 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>
Acked-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>