bindings: (hwmon/ltc2978.txt) add support for more parts (bindings)

Required properties:

- compatible: should contain one of:

  * "lltc,ltc2972"

  * "lltc,ltc2974"

  * "lltc,ltc2975"

  * "lltc,ltc2977"

  * "lltc,ltc2978"

  * "lltc,ltc2979"

  * "lltc,ltc2980"

  * "lltc,ltc3880"

  * "lltc,ltc3882"

  * "lltc,ltc3883"

  * "lltc,ltc3884"

  * "lltc,ltc3886"

  * "lltc,ltc3887"

  * "lltc,ltc3889"

  * "lltc,ltc7880"

  * "lltc,ltm2987"

  * "lltc,ltm4664"

  * "lltc,ltm4675"

  * "lltc,ltm4676"

  * "lltc,ltm4677"

  * "lltc,ltm4678"

  * "lltc,ltm4680"

  * "lltc,ltm4686"

  * "lltc,ltm4700"

- reg: I2C slave address

Optional properties:

  standard binding for regulators; see regulator.txt.

Valid names of regulators depend on number of supplies supported per device:

  * ltc2972 vout0 - vout1

  * ltc2974, ltc2975 : vout0 - vout3

  * ltc2977, ltc2980, ltm2987 : vout0 - vout7

  * ltc2977, ltc2979, ltc2980, ltm2987 : vout0 - vout7

  * ltc2978 : vout0 - vout7

  * ltc3880, ltc3882, ltc3886 : vout0 - vout1

  * ltc3880, ltc3882, ltc3884, ltc3886, ltc3887, ltc3889 : vout0 - vout1

  * ltc7880 : vout0 - vout1

  * ltc3883 : vout0

  * ltm4676 : vout0 - vout1

  * ltm4686 : vout0 - vout1

  * ltm4664 : vout0 - vout1

  * ltm4675, ltm4676, ltm4677, ltm4678 : vout0 - vout1

  * ltm4680, ltm4686 : vout0 - vout1

  * ltm4700 : vout0 - vout1

Example:

ltc2978@5e {