s390/seccomp: include generic seccomp header file

s390/seccomp: include generic seccomp header file

Fixes this build error on linux-next:

kernel/seccomp.c: In function '__secure_computing_strict':
kernel/seccomp.c:526:3: error: implicit declaration of function
				'get_compat_mode1_syscalls'

The retrieval of compat syscall numbers were moved into inline function
defined in asm-generic header but the asm-generic header is not being
used by s390.

[heiko.carstens@de.ibm.com]: even though the build error will trigger
only in the next merge window it makes sense to include the generic
header file already now.

Fixes: ("seccomp: Get compat syscalls from asm-generic header")
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>