ARM: dts: trimslice: sync SPI node with Linux dts

After "spi: spi_flash_probe_bus_cs() rely on DT for spi speed and mode"
series flash speed and mode wasn't passed to driver anymore, which
resulted in:

Loading Environment from SPIFlash... tegra20_sflash spi@7000c380: Invalid chip select 0:0 (err=-19)
*** Warning - spi_flash_probe_bus_cs() failed, using default environment

Fix it by syncing SPI node of affected device dts with Linux kernel dts.
The changed SPI bus frequency doesn't influence stability of read/write
operations.

Ref: https://patchwork.ozlabs.org/project/uboot/cover/20220518064648.1843664-1-patrice.chotard@foss.st.com


Signed-off-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Signed-off-by: Tom <twarren@nvidia.com>