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

This reverts commit cac21c3e which is
commit 027b57170bf8bb6999a28e4a5f3d78bf1db0f90c 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: e9adf72bdbd5 ("serial: core: Fix initializing and restoring termios speed")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I158a28eb7a1ac7892c836abcdbc178129de69391