dts: arm: mec1501hsz: rename I2C nodes

The I2C controllers on the MEC1501 SoC can be attached to
different I2C output line. For example, the I2C #0 controller
can be used with I2C7 physical lines out of SoC. The output
selection is done by the attribute "port_sel". This renames
the parent I2C nodes on the SoC side to refer to
the controller themselves instead of the output lines to
avoid confusion. The labels of these nodes are also renamed
to reflect the controllers.

On the board level, the DTS labels are overwritten to indicate
the actual output lines.

Aliases are also provided in both SoC and board levels to
provide shortcuts to the DTS nodes.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>