x86, boot: Remove ancient, unconditionally #ifdef'd out dead code

Release v1.3.82 wrapped a few lines of code in an "#ifdef
SAFE_RESET_DISK_CONTROLLER" and "#endif" pair. Since
SAFE_RESET_DISK_CONTROLLER was never defined anywhere that was basically
a verbose "#ifdef 0" and "#endif" pair. These dead lines have been in
the tree for sixteen years but now the time has come to remove them.

I guess the main lesson here is that if you want your dead code in the
tree for a very long time you'd better be creative. A plain old "#ifdef
0" and "#endif" pair just doesn't cut it!

See: http://lkml.kernel.org/r/199603301718.LAA00178@craie.inetnebr.com

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Link: http://lkml.kernel.org/r/1340230589.1773.7.camel@x61.thuisdomein
Acked-by: Jeff Epler <jepler@unpythonic.net>
Acked-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/boot/header.S

@@ -386,13 +386,6 @@ init_size:		.long INIT_SIZE		# kernel initialization size
 
 	.section ".entrytext", "ax"
 start_of_setup:
-#ifdef SAFE_RESET_DISK_CONTROLLER
-# Reset the disk controller.
-	movw	$0x0000, %ax		# Reset disk controller
-	movb	$0x80, %dl		# All disks
-	int	$0x13
-#endif
-
 # Force %es = %ds
 	movw	%ds, %ax
 	movw	%ax, %es