video: fbdev: atari: Remove backward bug-compatibility

As of v2.1.0, falcon_decode_var() contains a quirk to fix a rounding
error, as explained by Günther Kelleter on Fri, 30 Aug 1996:

This diff removes the now obsolete Falcon video option "pwrsave", and
fixes a rounding error that is triggered by the resolution switching X
server (those who use the pixel clock value 39722 in their /etc/fb.modes
should change it to 39721).

However, this causes the modified video mode returned by
falcon_decode_var() to not match the video mode returned by
falcon_encode_var(). Fix this by dropping the quirk.

Unfortunately /etc/fb.modes in fbset was never updated, so the
"640x480-60" mode still contains the wrong pixclock.
Hence this change may introduce a regression.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Tested-by: Michael Schmitz <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

drivers/video/fbdev/atafb.c

···
 	else if (yres_virtual < yres)
 		yres_virtual = yres;
 
-	/* backward bug-compatibility */
-	if (var->pixclock > 1)
-		var->pixclock -= 1;
-
 	par->hw.falcon.line_width = bpp * xres / 16;
 	par->hw.falcon.line_offset = bpp * (xres_virtual - xres) / 16;