By commit 6d8962e814,
label of _start was not usable in start.S and build fail.
This change label from _start to _sh_start.
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arch/sh/cpu/sh4/libsh4.o: In function `_start':
(.text+0x204): multiple definition of `_start'
arch/sh/cpu/sh4/start.o:(.text+0x0): first defined here
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Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
2024b968ee