sie.h was missing in arch/s390/include/uapi/asm/Kbuild and therefore missed
the "make headers_check" target.
If added it reveals that also arch/s390/include/asm/sigp.h would become uapi.
This is something we certainly do not want. So remove that dependency as well.

The header file was merged with ceae283b "KVM: s390: add sie exit
reasons tables", therefore we never had a kernel release with this commit and
can still change anything.
Acked-by: NAlexander Yarygin <yarygin@linux.vnet.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>