* Clone the board-specific files from those used for the STM3220G-EVAL board.
* Change STM3220G-EVAL to STM3240G-EVAL where appropriate.
* cpu/arm_cortexm3/stm32/clock.c: Add support for clock rates up to 168 MHz.
* Ethernet driver: Implement us/ms delays not tied to CPU clock rate.
* Ethernet driver: Add `stm_phy_wait_busy()` to reduce code duplication.
* Raise system clock rate from 120 MHz to 168 MHz.
* Update PSRAM timings.
* Disable the PSRAM Synchronous Burst Mode.