Support for BIOS interrupt handler

Support for BIOS interrupt handler

This patch implements the TCG BIOS interrupt handler 1ah. It is for
example used by trusted grub.

This patch adds an implementation of SHA1 (following NIST specs., IETF RFC 3147
and Wikipedia) for speeding up measurements of code. Trusted Grub for example
makes use of this interface and measures (calculates SHA1) of the Linux kernel
and initrd. Those files can be rather large and hunting their bytes through
the TIS interface as part of the int handler commands invoked by trusted grub
does take quite some time due to the many vmexits the interface is creating
(one per byte).

There is also a threshold for the size of data to hash (100k) below which
the TPM is used and above the internal faster SHA1 algorithm is used.

This patch for example enables trusted grub to interact with the TPM
and take additional measurements.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>