CONFIG_MICROCHIP_CLOCKSOURCE_PIT64B is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

64-bit Periodic Interval Timer (PIT64B) support

configname: CONFIG_MICROCHIP_CLOCKSOURCE_PIT64B

Linux Kernel Configuration
└─>AT91/Microchip SoCs
└─>64-bit Periodic Interval Timer (PIT64B) support
In linux kernel since version 5.2 (release Date: 2019-07-07)  
Select this to get a high resolution clockevent (SAM9X60) or
clocksource and clockevent (SAMA7G5) based on Microchip 64-bit
Periodic Interval Timer.