mx6: peripheral clock from oscillator

mx6: peripheral clock from oscillator

In order to be able to run the I2C bus at 400Khz, the chip errata[1]
recommends that the peripheral clock runs out of the 24MHz oscillator.

Systems running I2C from OP-TEE before Linux executes - for example to
access a Secure Element [2] providing the cryptographic support - expect
this clock to be configured by the bootloader [3].

[1] IMX6SLCE Rev. 5, 02/2019, ERR007805.
[2] OP-TEE: support for NXP SE05X Plug and Trust (patch on the list).
[3] OP-TEE: check the imx_i2c.c driver (imx6 patch on the list).

Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Reviewed-by: Fabio Estevam <festevam@gmail.com>