termios: consolidate values for VDISCARD in INIT_C_CC

On old systems it used to be ^O.  Linux had never actually used
the value, but INIT_C_CC (on i386) did initialize it to ^O;
unfortunately, it had a typo in the comment claiming that to be
^U.  Most of the architectures copied the (correct) definition
along with mistaken comment.  alpha, powerpc and sparc tried
to make the definition match comment.

However, util-linux still resets it to ^O on any architecture,
^O is the historical value, kernel ignores it anyway and finally,
Linus said "Just change everybody to do the same, nobody cares
about VDISCARD".

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/YxDmy//MKzs3ye7l@ZenIV


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