subsys: greybus: mikrobus changes for reading mikrobus manifest from clickid

Hi @jadonk ,

This PR has some more additonal changes for the Click ID adapter,

algorithm for reading manifest: read user eeprom byte(0x0A0A), this byte has start address of variable manifest(if this byte = 0 or invalid, this means no variable manifest) if (variable manifest available) read variable manifest and continue with mikrobus probe else (read fixed manfifest at addr 0x0000) enable via userspace using information in fixed manfiest