tile: normalize global variables exported by vmlinux.lds

Normalize global variables exported by vmlinux.lds to conform usage
guidelines from include/asm-generic/sections.h.

1) Use _text to mark the start of the kernel image including the head
text, and _stext to mark the start of the .text section.
2) Export mandatory global variables __init_begin and __init_end.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index 45ce26d..f2ac2f4 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -562,7 +562,7 @@
 			prot = ktext_set_nocache(prot);
 		}
 
-		BUG_ON(address != (unsigned long)_stext);
+		BUG_ON(address != (unsigned long)_text);
 		pte = NULL;
 		for (; address < (unsigned long)_einittext;
 		     pfn++, address += PAGE_SIZE) {