arm64: dts: ti: k3-am62a: Modify frequencies according to PHY

commit 2d6facf7f6b24b2e7a9b921b57ec6b50fc810637 from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



With PHY being tuned at a optimal tuning point, set the controller
frequency to operate at higher frequency possible and set the SPI
bus frequency to 25 MHz and respective read-delay.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>