debian/config: enable TPM-backed secure storage of cryptographic keys
Enable TPM 2.0 drivers and trusted/encrypted keys so the bianca kernel can seal cryptographic keys to the TPM:
- CONFIG_TCG_TPM=m (core TPM subsystem)
- CONFIG_TCG_TIS=m (TIS/FIFO interface)
- CONFIG_TCG_TIS_SPI=m (SPI TPM)
- CONFIG_TCG_TIS_I2C=m (I2C TPM)
- CONFIG_TCG_CRB=m (Command Response Buffer interface)
- CONFIG_TRUSTED_KEYS=m (TPM-sealed trusted keys)
- CONFIG_TRUSTED_KEYS_TPM=y (TPM backend for trusted keys)
- CONFIG_ENCRYPTED_KEYS=y (keys encrypted by trusted/user keys)
Also add Documentation/elxr/ guides for secure key storage, TPM setup/usage, and troubleshooting, and wire them into Documentation/index.rst.
Bump debian/changelog to 6.12.86-2.