MIPS: vmlinux.lds.S: remove duplicate _sdata symbol

_sdata is defined twice in vmlinux.lds.S. According to vmlinux.ld.h
in asm-generic, _sdata should be marked at the beginning RO_DATA_SECTION.

 *      _sdata = .;
 *      RO_DATA_SECTION(PAGE_SIZE)
 *      RW_DATA_SECTION(...)
 *      _edata = .;

Remove the one that is marked at RW_DATA_SECTION.
Signed-off-by: Tony Wu <tung7970@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3215/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/vmlinux.lds.S

@@ -69,7 +69,6 @@ SECTIONS
 	RODATA
 
 	/* writeable */
-	_sdata = .;				/* Start of data section */
 	.data : {	/* Data */
 		. = . + DATAOFFSET;		/* for CONFIG_MAPPED_KERNEL */