UBUNTU: SAUCE: s390: update zfcpdump_defconfig

UBUNTU: SAUCE: s390: update zfcpdump_defconfig

BugLink: http://bugs.launchpad.net/bugs/1719290
Starting with v4.13 generating a kernel config with the seed-file
zfcpdump_defconfig does not include CONFIG_DEBUG_FS anymore. Standalone
dump will not be possible w/o that option, so re-enable it again
explicitely.

Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Acked-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>