ARM: dts: turris-omnia: Add atsha204a node

Crypto module atsha204a is available at i2c address 0x64. Module is used
for symmetric cryptography and provides also hardware random number
generator and OTP storage for device serial number and MAC addresses.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>