mm/bootmem.c: cosmetic improvement of code readability

The obvious number of bits in a byte is replaced by BITS_PER_BYTE macro
in bootmap_bytes()

Link: http://lkml.kernel.org/r/1483781600-5136-1-git-send-email-ondar07@gmail.comSigned-off-by: Adygzhy Ondar <ondar07@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/bootmem.c

@@ -53,7 +53,7 @@ early_param("bootmem_debug", bootmem_debug_setup);
 
 static unsigned long __init bootmap_bytes(unsigned long pages)
 {
-	unsigned long bytes = DIV_ROUND_UP(pages, 8);
+	unsigned long bytes = DIV_ROUND_UP(pages, BITS_PER_BYTE);
 
 	return ALIGN(bytes, sizeof(long));
 }