Revert "serial: core: Fix initializing and restoring termios speed"

This reverts commit cac21c3e which is
commit 027b5717 upstream.

It breaks the kernel abi and is not something that is necessary in
Android systems, so it is safe to revert.

Bug: 161946584
Fixes: e9adf72b ("serial: core: Fix initializing and restoring termios speed")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I158a28eb7a1ac7892c836abcdbc178129de69391