mdadm: super-ddf.c fix coverity issues

mdadm: super-ddf.c fix coverity issues

Fixing the following coding errors the coverity tools found:

* Calling "lseek64" without checking return value. This library function may
fail and return an error code.
* Overrunning array "anchor->pad2" of 3 bytes by passing it to a function
which accesses it at byte offset 398 using argument "399UL".
* Event leaked_storage: Variable "sra" going out of scope leaks the storage
it points to.
* Event leaked_storage: Variable "super" going out of scope leaks the storage
it points to.
* Event leaked_handle: Handle variable "dfd" going out of scope leaks the
handle.
* Event leaked_storage: Variable "dl1" going out of scope leaks the storage
it points to
* Event leaked_handle: Handle variable "cfd" going out of scope leaks the
handle.
* Variable "avail" going out of scope leaks the storage it points to.
* Passing unterminated string "super->anchor.revision" to "fprintf", which
expects a null-terminated string.
* You might overrun the 32-character fixed-size string "st->container_devnm"
by copying the return value of "fd2devnm" without checking the length.
* Event fixed_size_dest: You might overrun the 33-character fixed-size string
"dev->name" by copying "(*d).devname" without checking the length.
* Event uninit_use_in_call: Using uninitialized value "info.array.raid_disks"
when calling "getinfo_super_ddf"

V2: clean up validate_geometry_ddf() routine with Mariusz Tkaczyk recommendations.
V3: clean up spaces with Blazej Kucman recommendations.
V4: clean up recommended by Mariusz Tkaczyk.
V5: clean up recommended by Mariusz Tkaczyk.

Signed-off-by: Nigel Croxon <ncroxon@redhat.com>