[S390] sclp: fix compile error for !SCLP_CONSOLE

Define an empty static inline version of sclp_console_pm_event()
to fix the build error below for !SCLP_CONSOLE.

drivers/s390/built-in.o: In function `sclp_rw_pm_event':
sclp_rw.c:(.text+0x12f68): undefined reference to `sclp_console_pm_event'

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>