scsi: qedi: fix build error without DEBUG_FS

Without CONFIG_DEBUG_FS, we run into a link error:

drivers/scsi/qedi/qedi_iscsi.o: In function `qedi_ep_poll':
qedi_iscsi.c:(.text.qedi_ep_poll+0x134): undefined reference to `do_not_recover'
drivers/scsi/qedi/qedi_iscsi.o: In function `qedi_ep_disconnect':
qedi_iscsi.c:(.text.qedi_ep_disconnect+0x36c): undefined reference to `do_not_recover'
drivers/scsi/qedi/qedi_iscsi.o: In function `qedi_ep_connect':
qedi_iscsi.c:(.text.qedi_ep_connect+0x350): undefined reference to `do_not_recover'
drivers/scsi/qedi/qedi_fw.o: In function `qedi_tmf_work':
qedi_fw.c:(.text.qedi_tmf_work+0x3b4): undefined reference to `do_not_recover'

This defines the symbol as a constant in this case, as there is no way to
set it to anything other than zero without DEBUG_FS. In addition, I'm renaming
it to qedi_do_not_recover in order to put it into a driver specific namespace,
as "do_not_recover" is a really bad name for a kernel-wide global identifier
when it is used only in one driver.

Fixes: ace7f46b ("scsi: qedi: Add QLogic FastLinQ offload iSCSI driver framework.")
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Manish Rangankar <Manish.Rangankar@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>