src: Remove duplicated round up function

This removes CEIL_DIV and div_round_up() altogether and
replace it by DIV_ROUND_UP defined in commonlib/helpers.h.

Change-Id: I9aabc3fbe7834834c92d6ba59ff0005986622a34
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/29847
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/include/stdlib.h

@@ -11,12 +11,4 @@ void *malloc(size_t size);
 /* We never free memory */
 static inline void free(void *ptr) {}
 
-#ifndef __ROMCC__
-static inline unsigned long div_round_up(unsigned int n, unsigned int d)
-{
-	return (n + d - 1) / d;
-}
-#endif
-
-
 #endif /* STDLIB_H */