[PATCH] tpm: check mem start and len

The memory start and length values obtained from the ACPI entry need to be
checked and filled in with the default values from the specification if
they don't exist.  This patch fills in the default values and uses them
appropriately.

Signed-off-by: Kylie Hall <kjhall@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>