doc: i2c: gpio: Document deblock sequence on probe

Document the gpio-i2c deblocking sequence binding.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/doc/device-tree-bindings/i2c/i2c-gpio.txt b/doc/device-tree-bindings/i2c/i2c-gpio.txt
index ba56ed5..e29eeba 100644
--- a/doc/device-tree-bindings/i2c/i2c-gpio.txt
+++ b/doc/device-tree-bindings/i2c/i2c-gpio.txt
@@ -16,6 +16,8 @@
    The resulting transfer speed can be adjusted by setting the delay[us]
    between gpio-toggle operations. Speed [Hz] = 1000000 / 4 * udelay[us],
    It not defined, then default is 5us (~50KHz).
+* i2c-gpio,deblock
+   Run deblocking sequence when the driver gets probed.
 
 Example: