Make Xkb{Get,Set}NamedIndicator spec & manpages match code

The XKB Library spec and the man pages for XkbGetNamedIndicator &
XkbSetNamedIndicator included a device_spec argument neither function
takes, and do not include the XkbGetNamedDeviceIndicator &
XkbSetNamedDeviceIndicator variants that do take it (along with two
other arguments).

This updates them to match the interfaces the code has provided for
decades.

This has been reported multiple times, so this fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=251
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=729812


Sun Bug 4528016 XkbSetNamedIndicator & XkbGetNamedIndicator man pages are wrong
  (filed: alan.coopersmith@sun.com 2001-11-15 - now aka Oracle bug 15087506)
X.Org Group Defect Id #9418

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>