kernel.h: implement DIV_ROUND_CLOSEST_ULL

We have grown a number of different implementations of
DIV_ROUND_CLOSEST_ULL throughout the kernel. Move the i915 one to
kernel.h so that it can be reused.

Signed-off-by: Javi Merino <[e-mail]>
Reviewed-by: Jeff Epler <[e-mail]>
Cc: Jani Nikula <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Alex Elder <[e-mail]>
Cc: Antti Palosaari <[e-mail]>
Cc: Javi Merino <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Mike Turquette <[e-mail]>
Cc: Stephen Boyd <[e-mail]>
Cc: Stephen Hemminger <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/gpu/drm/i915/intel_drv.h

···
 #include <drm/drm_dp_mst_helper.h>
 #include <drm/drm_rect.h>
 
-#define DIV_ROUND_CLOSEST_ULL(ll, d)	\
-({ unsigned long long _tmp = (ll)+(d)/2; do_div(_tmp, d); _tmp; })
-
 /**
  * _wait_for - magic (register) wait macro
  *

drivers/gpu/drm/i915/intel_panel.c

···
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include "intel_drv.h"
 

include/linux/kernel.h

···
 		(((__x) - ((__d) / 2)) / (__d));	\
 }							\
 )
+/*
+ * Same as above but for u64 dividends. divisor must be a 32-bit
+ * number.
+ */
+#define DIV_ROUND_CLOSEST_ULL(x, divisor)(		\
+{							\
+	typeof(divisor) __d = divisor;			\
+	unsigned long long _tmp = (x) + (__d) / 2;	\
+	do_div(_tmp, __d);				\
+	_tmp;						\
+}							\
+)
 
 /*
  * Multiplies an integer by a fraction, while avoiding unnecessary