i2c: mlxcpld: Fix wrong initialization order in probe

Fix wrong order in probing routine initialization - field `base_addr'
is used before it's initialized. Move assignment of 'priv->base_addr`
to the beginning, prior the call to mlxcpld_i2c_read_comm().
Wrong order caused the first read of capability register to be executed
at wrong offset 0x0 instead of 0x2000. By chance it was a "good
garbage" at 0x0 offset.

Fixes: 313ce648 ("i2c: mlxcpld: Add support for extended transaction length for i2c-mlxcpld")
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org