CONFIG_MACH_BERLIN_BG2 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Marvell Armada 1500 (BG2)

modulename: bg2.ko

and/or

configname: CONFIG_MACH_BERLIN_BG2

Linux Kernel Configuration
└─>Marvell Berlin SoC variants
└─>Marvell Armada 1500 (BG2)
In linux kernel since version 3.10 (release Date: 2013-06-30)