fbdev: use DIV_ROUND_UP or roundup

The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
(d)) but is perhaps more readable.

An extract of the semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
expression n,d;
@@

(
- (n + d - 1) / d
+ DIV_ROUND_UP(n,d)
|
- (n + (d - 1)) / d
+ DIV_ROUND_UP(n,d)
)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP((n),d)
+ DIV_ROUND_UP(n,d)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP(n,(d))
+ DIV_ROUND_UP(n,d)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/video/atafb.c b/drivers/video/atafb.c
index 5d4fbaa..dff3547 100644
--- a/drivers/video/atafb.c
+++ b/drivers/video/atafb.c
@@ -1270,7 +1270,7 @@
 
 	gstart = (prescale / 2 + plen * left_margin) / prescale;
 	/* gend1 is for hde (gend-gstart multiple of align), shifter's xres */
-	gend1 = gstart + ((xres + align - 1) / align) * align * plen / prescale;
+	gend1 = gstart + roundup(xres, align) * plen / prescale;
 	/* gend2 is for hbb, visible xres (rest to gend1 is cut off by hblank) */
 	gend2 = gstart + xres * plen / prescale;
 	par->HHT = plen * (left_margin + xres + right_margin) /