ARM: mvebu: NETGEAR ReadyNAS 102 .dts cleanup

The patch does some cleanup work on NETGEAR ReadyNAS 102 .dts
file. Changes are listed below

 - Added missing button mpp in pinctrl
 - Converted from value to macros for GPIO voltage level
 - Converted all numeric input key values to macros
 - Added GPIO keys pins to pinctrl
 - Made button names more explicit
 - Document ethernet PHY (Marvell 88E1318) via a comment
 - Made G762 clock node name unique by including g762 in it
 - Fixed all node names and labels to use respectively '-' and '_'
 - Changed order of included files from general to local
 - Removed useless clocks and gpio-keys properties

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>