dts: Add missing spi-max-frequency for mimxrt/nxp/hifive1/qemu_riscv2

spi-max-frequency is marked as required in
dts/bindings/mtd/jedec,spi-nor.yaml.

I took the value from the datasheets (133 MHz for all), and guessed that
a dummy entry is fine for QEMU.

Fixes some errors in
https://github.com/zephyrproject-rtos/zephyr/issues/17532

.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>