Revert "serial: mctrl_gpio: split disable_ms into sync and no_sync APIs"

This reverts commit c504c11b which is
commit 1bd2aad5 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ibbe2f934d5647a431cc23a9ae46b1dbc335168b5
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>