EEPROM supported in MTD interface

@tridge @DrTon Could you please give this a review? It creates this device on the FMUv1.x EEPROM:

```
mtd: Flash Geometry:
  blocksize:      32
  erasesize:      32
  neraseblocks:   256
  No. partitions: 2
  Partition size: 128 Blocks (4096 bytes)
  TOTAL SIZE: 8 KiB
```