[Slave] Add a full example for lan9252 on Freedom-K64F

[leducp]

[trns1997]

• [ ] Fill the RxPDOs (0x6000–0x6005) with current accelerometer and magnetometer values (accel_x, accel_y, accel_z, mag_x, mag_y, mag_z) so the master can read them.
• [ ] Read the TxPDOs (0x7000–0x7002) to get the LED states (LED_R, LED_G, LED_B) and update the physical LEDs accordingly.