checks: Improve i2c reg property checking

The i2c bindings in the kernel tree describe support for 10 bit
addressing, which must be indicated with the I2C_TEN_BIT_ADDRESS flag.
When this is set the address can be up to 10 bits. When it is not set
the address is a maximum of 7 bits.

See Documentation/devicetree/bindings/i2c/i2c.txt.

Take into account this flag when checking the address is valid.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Message-Id: <20200622031005.1890039-3-joel@jms.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>