xtensa: replace xtensa-specific _f{data,text} by _s{data,text}

commit a2d063ac ("extable, core_kernel_data(): Make sure all archs
define _sdata") missed xtensa.  Xtensa does have a start of data marker,
but calls it _fdata, causing

    kernel/built-in.o:(.text+0x964): undefined reference to `_sdata'

_stext was already defined, but it was duplicated by _fdata.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/xtensa/kernel/vmlinux.lds.S

@@ -83,7 +83,6 @@ SECTIONS
 
   _text = .;
   _stext = .;
-  _ftext = .;
 
   .text :
   {
@@ -112,7 +111,7 @@ SECTIONS
   EXCEPTION_TABLE(16)
   /* Data section */
 
-  _fdata = .;
+  _sdata = .;
   RW_DATA_SECTION(XCHAL_ICACHE_LINESIZE, PAGE_SIZE, THREAD_SIZE)
   _edata = .;
 

arch/xtensa/mm/init.c

@@ -29,7 +29,7 @@
 
 /* References to section boundaries */
 
-extern char _ftext, _etext, _fdata, _edata, _rodata_end;
+extern char _stext, _etext, _sdata, _edata, _rodata_end;
 extern char __init_begin, __init_end;
 
 /*
@@ -197,8 +197,8 @@ void __init mem_init(void)
 			reservedpages++;
 	}
 
-	codesize =  (unsigned long) &_etext - (unsigned long) &_ftext;
-	datasize =  (unsigned long) &_edata - (unsigned long) &_fdata;
+	codesize =  (unsigned long) &_etext - (unsigned long) &_stext;
+	datasize =  (unsigned long) &_edata - (unsigned long) &_sdata;
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
 	printk("Memory: %luk/%luk available (%ldk kernel code, %ldk reserved, "