Consolidate strmhz() implementation

ARM, i386, m68k and ppc all have identical implementations of strmhz().
Other architectures don't provide this function at all.

This patch moves strmhz() into lib_generic, reducing code duplication
and providing a more unified API across architectures.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

lib_arm/board.c

@@ -115,19 +115,6 @@ void *sbrk (ptrdiff_t increment)
 	return ((void *) old);
 }
 
-char *strmhz(char *buf, long hz)
-{
-	long l, n;
-	long m;
-
-	n = hz / 1000000L;
-	l = sprintf (buf, "%ld", n);
-	m = (hz % 1000000L) / 1000L;
-	if (m != 0)
-		sprintf (buf + l, ".%03ld", m);
-	return (buf);
-}
-
 
 /************************************************************************
  * Coloured LED functionality