sh: Fix clone exit return code (BZ #22605)

Since 3f823e87 (Call exit directly in clone (BZ #21512)) SH clone
implementation fails to set the exit code resulting in the failures:

FAIL: nptl/tst-align-clone
FAIL: nptl/tst-getpid1

This patch fixes the both testcases.

	[BZ #22605]
	* sysdeps/unix/sysv/linux/sh/clone.S (__clone): Fix exit return
	code.

Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>