Now that the cpu_ld/st_* function directly call helper_ret_ld/st, we can
drop the old helper_ld/st functions.

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150710095656.13280.7085.stgit@PASHA-ISP>
Signed-off-by: Richard Henderson <rth@twiddle.net>