s390/syscalls: Add pt_regs parameter to SYSCALL_DEFINE0() syscall wrapper

s390/syscalls: Add pt_regs parameter to SYSCALL_DEFINE0() syscall wrapper

All system call wrappers should match the sys_call_ptr_t type. This is not
the case for system calls without parameters. Add the missing pt_regs
parameter there too.

Note: this is currently not a problem, since the parameter is unused.
However it prevents to create a correctly typed system call table in
C. With the current assembler implementation this works because of
missing type checking.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>