`load_wait_psw` is defined in include/boot/s390.h but is implemented in
zipl/boot/libc.c. This results in a dangling definition for s390.h users
other than zipl, due to the missing implementation. Since the function
is only relevant for zipl, move the definition to the corresponding
header file zipl/boot/libc.h
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
dad7fce7a1