[TPM] Set tcpa calls in the rombios and other fixes.

[TPM] Set tcpa calls in the rombios and other fixes.

This patch places some tcpa calls into the rombios that had previously
not applied anymore or were not set.
Force the reads from MMIO memory locations that the compiler otherwise
optimizes away (-O2) if there was an immediate write to the same
memory location before.
Use #define'd constants wherever possible.
Fix all remaining compiler warnings.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>