ARM: dts: imx8mp-beacon-kit-u-boot: Drop EQoS clock work-around

Since commit ecb1c37a ("clk: imx8mp: Add EQoS MAC clock"),
the clocks for the DWMAC driver can be configured, and removing
them breaks operation.

Fixes: ecb1c37a ("clk: imx8mp: Add EQoS MAC clock")
Suggested-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>