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/include/asm/sections.h b/arch/tile/include/asm/sections.h
index d062d46..7d8a935 100644
--- a/arch/tile/include/asm/sections.h
+++ b/arch/tile/include/asm/sections.h
@@ -34,7 +34,7 @@
 extern char __start_atomic_asm_code[], __end_atomic_asm_code[];
 #endif
 
-/* Handle the discontiguity between _sdata and _stext. */
+/* Handle the discontiguity between _sdata and _text. */
 static inline int arch_is_kernel_data(unsigned long addr)
 {
 	return addr >= (unsigned long)_sdata &&