Drop the hard-coded value of 1146 lines which seems to work with HP-UX
11, but not with HP-UX 10. Instead encode the screen height in byte 0 of
active_lines_low and byte 3 of misc_video as it's expected by the Xorg
X11 graphics driver.
This potentially allows for higher vertical screen resolutions than
1280x1024 with X11.
Signed-off-by: Helge Deller <deller@gmx.de> Acked-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>