arm64: dts: ti: k3-am625-phyboard-lyra-rdk: Lower I2C1 frequency

The gpio-expander on i2c-1 has a maximum frequency of 100kHz. Update our
main_i2c1 frequency to allow the nxp,pcf8574 gpio-expander to function
properly.
Signed-off-by: Garrett Giordano <ggiordano@phytec.com>
Reviewed-by: Wadim Egorov <w.egorov@phytec.de>
Link: https://lore.kernel.org/r/20231204222811.2344460-1-ggiordano@phytec.comSigned-off-by: Nishanth Menon <nm@ti.com>

arch/arm64/boot/dts/ti/k3-am625-phyboard-lyra-rdk.dts

@@ -187,7 +187,7 @@ cpsw3g_phy3: ethernet-phy@3 {
 &main_i2c1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&main_i2c1_pins_default>;
-	clock-frequency = <400000>;
+	clock-frequency = <100000>;
 	status = "okay";
 
 	gpio_exp: gpio-expander@21 {