linux-milo: Upgrade to 3.12

Merged latest ADI kernel.
Adapted defconfig for zedboard using menuconfig.
(note: zc702 defconfig not updated yet, will not work because the driver
names have been changed. To fix, run menuconfig and add these back, see
the zed defconfig for the changes required)
zedboard: Add PModOLED to drivers in defconfig

Build the OLED driver as module so that the logo is displayed once more.
Use 3.12 kernel for zedboard

The defconfig for zc702 isn't ready, so use the 3.10 on that board
until that's done.