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>

arch/tile/kernel/vmlinux.lds.S

@@ -27,7 +27,6 @@ SECTIONS
   .intrpt1 (LOAD_OFFSET) : AT ( 0 )   /* put at the start of physical memory */
   {
     _text = .;
-    _stext = .;
     *(.intrpt1)
   } :intrpt1 =0
 
@@ -36,6 +35,7 @@ SECTIONS
 
   /* Now the real code */
   . = ALIGN(0x20000);
+  _stext = .;
   .text : AT (ADDR(.text) - LOAD_OFFSET) {
     HEAD_TEXT
     SCHED_TEXT
@@ -58,11 +58,13 @@ SECTIONS
   #define LOAD_OFFSET PAGE_OFFSET
 
   . = ALIGN(PAGE_SIZE);
+  __init_begin = .;
   VMLINUX_SYMBOL(_sinitdata) = .;
   INIT_DATA_SECTION(16) :data =0
   PERCPU_SECTION(L2_CACHE_BYTES)
   . = ALIGN(PAGE_SIZE);
   VMLINUX_SYMBOL(_einitdata) = .;
+  __init_end = .;
 
   _sdata = .;                   /* Start of data section */