CONFIG_MACH_AML_M5900 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AML M5900 Series

modulename: mach-amlm5900.ko

configname: CONFIG_MACH_AML_M5900

Linux Kernel Configuration
└─>S3C24XX Implementations
└─>AML M5900 Series
In linux kernel since version 2.6.19 (release Date: 2006-11-29)  
Say Y here if you are using the American Microsystems M5900 Series
<http://www.amltd.com>

source code:
arch/arm/mach-s3c2410/mach-amlm5900.c