Provide keyring for platform/firmware trusted keys

configname: CONFIG_INTEGRITY_PLATFORM_KEYRING

Linux Kernel Configuration
└─>Security options
└─>Provide keyring for platform/firmware trusted keys
In linux kernel since version 5 (release Date: 2019-03-03)  
Provide a separate, distinct keyring for platform trusted keys, which
the kernel automatically populates during initialization from values
provided by the platform for verifying the kexec'ed kerned image
and, possibly, the initramfs signature.