ARM: imx: verdin-imx8mm: Set CAN oscillator frequency based on model

ARM: imx: verdin-imx8mm: Set CAN oscillator frequency based on model

The older i.MX8M Mini Verdin SoMs may came with 20 MHz SPI CAN controller
oscillator, the newer SoMs always use 40 MHz oscillator. Handle both by
overriding the oscillator frequency just before booting the kernel.

These are the known variants with 20 MHz oscillator:
- 0055, V1.1A, V1.1B, V1.1C and V1.1D, use a 20MHz oscillator
- 0059, V1.1A and V1.1B, use a 20MHz oscillator

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>