_TSS was erroneously ignored, in favor of the FADT.

When TSS is used, the access width is included in the PTC control/status
register.  So it is unnecessary that the access bit width is multiplied by 8.
At the same time the bit_offset should be considered for system I/O Access.

It should be checked the bit_width and bit_offset of PTC regsiter in order to
avoid the failure of system I/O access. It means that bit_width plus
bit_offset can't be greater than 32.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Li Shaohua <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>