boards: m5stack_core2: Increase i2c bitrate on i2c0

All periphals connected on i2c0 support 400kbit. The default speed has
been increased to improve responsiveness.

(cherry picked from commit 555baf7)

Original-Signed-off-by: Martin Kiepfer <m.kiepfer@teleschirm.org>
GitOrigin-RevId: 555baf7
Change-Id: Ie7502781b5c73335d1643100768e2792e0c80fb8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5407197
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>

boards/xtensa/m5stack_core2/m5stack_core2.dts

@@ -85,7 +85,7 @@
 
 &i2c0 {
 	status = "okay";
-	clock-frequency = <I2C_BITRATE_STANDARD>;
+	clock-frequency = <I2C_BITRATE_FAST>;
 	sda-gpios = <&gpio0 21 GPIO_OPEN_DRAIN>;
 	scl-gpios = <&gpio0 22 GPIO_OPEN_DRAIN>;
 	pinctrl-0 = <&i2c0_default>;