sh: Kill off the .stack section.

We had a special .stack section in the ld script that
was being used to position r15 initially. This is
nonsensical, as we can just use a THREAD_SIZE offset
from the init_thread_union instead (as every other arch
does).
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/head.S

@@ -69,7 +69,7 @@ ENTRY(_stext)
 
 	.balign 4
 1:	.long	0x400080F0		! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
-2:	.long	stack
+2:	.long	init_thread_union+8192
 3:	.long	__bss_start
 4:	.long	_end
 5:	.long	start_kernel

arch/sh/kernel/vmlinux.lds.S

@@ -62,8 +62,6 @@ SECTIONS
 
   . = ALIGN(8192);		/* init_task */
   .data.init_task : { *(.data.init_task) }
-  /* stack */
-  .stack : { stack = .;  _stack = .; }
 
   . = ALIGN(4096);		/* Init code and data */
   __init_begin = .;