fix(chip): High-Z selected pad
fix(chip): High-Z selected pad

Add a protection code to make High-Z for the victim before entering a
low power mode.

For example, UARTs are enabled, they should be off for the chip to wake
from UART TX (oe is set).

Signed-off-by: Eunchan Kim <cb7bc7ceb22698f298c67faa994fd9ddf3cab298@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan