x86/boot: Fix pr_debug() API braindamage

What looked like a straightforward conversion from printk(KERN_DEBUG, ...)
to pr_debug() broke the boot log output:

  DMI:    /M57SLI-S4, BIOS FF 01/24/2008
 -e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
 -e820: remove [mem 0x000a0000-0x000fffff] usable
 +usable ==> reserved
 +usable
  e820: last_pfn = 0x230000 max_arch_pfn = 0x400000000

 ...

  x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- WT
 -e820: update [mem 0xd0000000-0xffffffff] usable ==> reserved
 +usable ==> reserved

i.e. spurious (and nonsensical) kernel log entries were created...

We need a pr_debug_and_I_mean_it() function which does nothing but
printk(KERN_DEBUG...

Signed-off-by: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
[ Wrote changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/e820.c

@@ -411,7 +411,7 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
 		size = ULLONG_MAX - start;
 
 	end = start + size;
-	pr_debug("e820: update [mem %#010Lx-%#010Lx] ", start, end - 1);
+	printk(KERN_DEBUG "e820: update [mem %#010Lx-%#010Lx] ", start, end - 1);
 	e820_print_type(old_type);
 	pr_cont(" ==> ");
 	e820_print_type(new_type);
@@ -487,7 +487,7 @@ u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool
 		size = ULLONG_MAX - start;
 
 	end = start + size;
-	pr_debug("e820: remove [mem %#010Lx-%#010Lx] ", start, end - 1);
+	printk(KERN_DEBUG "e820: remove [mem %#010Lx-%#010Lx] ", start, end - 1);
 	if (check_type)
 		e820_print_type(old_type);
 	pr_cont("\n");
@@ -1121,7 +1121,7 @@ void __init e820__reserve_resources_late(void)
 		if (start >= end)
 			continue;
 
-		pr_debug("e820: reserve RAM buffer [mem %#010llx-%#010llx]\n", start, end);
+		printk(KERN_DEBUG "e820: reserve RAM buffer [mem %#010llx-%#010llx]\n", start, end);
 		reserve_region_with_split(&iomem_resource, start, end, "RAM buffer");
 	}
 }