linux-wandboard

[S390] user-copy optimization fallout.

Fix new restore_sigregs function. It copies the user space copy of the
old psw without correcting the psw.mask and the psw.addr high order bit.
While we are at it, simplify save_sigregs a bit.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>