cciss: fix build for PROC_FS disabled

The recent patch to fix the removal of a non-existing proc
directory introduced this build problem for !CONFIG_PROC_FS:

drivers/block/cciss.c:4929: error: 'proc_cciss' undeclared (first use in this function)

Fix it by moving proc_cciss outside of the CONFIG_PROC_FS scope.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>