powerpc/fsl/dts: add missing P4080DS I2C devices

This just adds the zl2006 voltage regulators / power monitors and the
onboard I2C eeproms.  The ICS9FG108 clock chip doesn't seem to have a
driver, so it is left in the DTS as a comment.  And for good measure,
the SPD eeproms are tagged as such.

Signed-off-by: David Lamparter <equinox@diac24.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20180920230422.GK487685@eidolon.nox.tf