i2c: mlxcpld: Allow configurable adapter id for mlxcpld

It allows mlxcpld driver to be connected to pre-defined adapter number
equal or greater than one, in order to avoid current limitation, assuming
usage of id number one only.

Signed-off-by: Michael Shych <michaelsh@mellanox.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>