termbits.h: Remove posix_types.h include

Nothing in termbits seems to require anything from linux/posix_types.h.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220509093446.6677-4-ilpo.jarvinen@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>