s390: add a couple of useful defconfigs

Add four more defconfigs which we maintained outside of
the kernel tree for no good reason.
Inside of the kernel tree they can be easily used:

make whatever_defconfig

"make help" shows the available defconfigs.

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

diff --cc arch/s390/configs/default_defconfig
Simple merge

diff --cc arch/s390/configs/gcov_defconfig
Simple merge

diff --cc arch/s390/configs/performance_defconfig
Simple merge

diff --cc arch/s390/configs/zfcpdump_defconfig
Simple merge