x86_64: Squash initial_code modpost warnings

Get rid of warnings like

WARNING: vmlinux.o(.bootstrap.text+0x1a8): Section mismatch: reference to .init.text:x86_64_start_kernel (between 'initial_code' and 'init_rsp')

- Move initialization code into .text.head like i386 because modpost knows about this already
- Mark initial_code .initdata

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index e7a5eb6..ba8ea97 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -28,7 +28,7 @@
   _text = .;			/* Text and read-only data */
   .text :  AT(ADDR(.text) - LOAD_OFFSET) {
 	/* First the code that has to be first for bootstrapping */
-	*(.bootstrap.text)
+	*(.text.head)
 	_stext = .;
 	/* Then the rest */
 	TEXT_TEXT