CONFIG_MACH_ARMADA_370_XP is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Marvell Armada 370 and Aramada XP boards

modulename: armada-370-xp.ko

configname: CONFIG_MACH_ARMADA_370_XP

Linux Kernel Configuration
└─>Marvell SOC with device tree
└─>Marvell Armada 370 and Aramada XP boards
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say 'Y' here if you want your kernel to support boards based on
Marvell Armada 370 or Armada XP with device tree.

source code: