Verity data device root hash signature verification support

configname: CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG

Linux Kernel Configuration
└─>Device Drivers
└─>Multiple devices driver support (RAID and LVM)
└─>Verity data device root hash signature verification support
In linux kernel since version 5.1 (release Date: 2019-05-05)  
Add ability for dm-verity device to be validated if the
pre-generated tree of cryptographic checksums passed has a pkcs#7
signature file that can validate the roothash of the tree.

If unsure, say N.

selects
CONFIG_SYSTEM_DATA_VERIFICATION