eepflash.sh: Use i2c bus 10 to avoid clash on Pi 4

This script used to create a bit-bashed I2C interface in the event
that I2C0 was not already enabled. Because the kernel knew of three
I2C interfaces already the soft interface appeared as i2c-3. On Pi
4 the highest numbered I2C interface is i2c-6, which causes the
soft interface to appear as i2c-7.

Work around the issue by giving the soft interface an explicit
bus number of 10, guaranteeing that it won't clash on any known
system.

See: #65

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

eepromutils/eepflash.sh

@@ -105,19 +105,19 @@ modprobe i2c_dev
 if [ "$BUS" = "NOT_SET" ]; then
 	if [ -e "/dev/i2c-0" ]; then
 		BUS=0
-	elif [ -e "/dev/i2c-3" ]; then
-		BUS=3
+	elif [ -e "/dev/i2c-10" ]; then
+		BUS=10
 	else
-		dtoverlay i2c-gpio i2c_gpio_sda=0 i2c_gpio_scl=1
+		dtoverlay i2c-gpio i2c_gpio_sda=0 i2c_gpio_scl=1 bus=10
 		rc=$?
 		if [ $rc != 0 ]; then
 			echo "Loading of i2c-gpio dtoverlay failed. Do an rpi-update (and maybe apt-get update; apt-get upgrade)."
 			exit $rc
 		fi
-		if [ -e "/dev/i2c-3" ]; then
-			BUS=3
+		if [ -e "/dev/i2c-10" ]; then
+			BUS=10
 		else
-			echo "Expected I2C bus (i2c-3) not found."
+			echo "Expected I2C bus (i2c-10) not found."
 		fi
 	fi
 fi