python: fix termios build for xtensa

The xtensa ioctls.h header references struct serial_multiport_struct that is
not defined in this header or included headers. ioctls.h also references
tty_struct that is not exported to userspace at all. Add a patch fixing these
issues.

This is only a workaround as the real problem should be fixed in the kernel
(by removing all struct references like all other archs). But since we support
older kernel versions we'll have to carry this patch for some time.

Fixes:
http://autobuild.buildroot.net/results/12b/12b5612828d7f1fc7d1f69fc01341d5a6e628db5/



Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>