tpm_bios.c: make 2 structs static

This patch makes two needlessly global structs static.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Marcel Selhorst <tpm@selhorst.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>