x86: cleanup - eliminate numbers in LDT allocation code

This patch eliminates numbers in LDT allocation code
trying to make it clear to understand from where
these numbers come.

No code changed:

   text    data     bss     dec     hex filename
   1896       0       0    1896     768 ldt.o.before
   1896       0       0    1896     768 ldt.o.after
md5:
 6cbec8705008ddb4b704aade60bceda3  ldt.o.before.asm
 6cbec8705008ddb4b704aade60bceda3  ldt.o.after.asm

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/ldt.c

@@ -35,7 +35,8 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
 	if (mincount <= pc->size)
 		return 0;
 	oldsize = pc->size;
-	mincount = (mincount + 511) & (~511);
+	mincount = (mincount + (PAGE_SIZE / LDT_ENTRY_SIZE - 1)) &
+			(~(PAGE_SIZE / LDT_ENTRY_SIZE - 1));
 	if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
 		newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
 	else