sparc: Fix fork/clone/vfork system call restart.

We clobber %i1 as well as %i0 for these system calls,
because they give two return values.

Therefore, on error, we have to restore %i1 properly
or else the restart explodes since it uses the wrong
arguments.

This fixes glibc's nptl/tst-eintr1.c testcase.

Signed-off-by: David S. Miller <davem@davemloft.net>