mdadm: fix build failures (ppc64)

mdadm: fix build failures (ppc64)

This patch fixes these build issues:

super-intel.c: In function 'getinfo_super_imsm_volume':
super-intel.c:2327:4: error: format '%llu' expects argument of type 'long long
unsigned int', but argument 3 has type '__u64' [-Werror=format]

super-intel.c: In function 'imsm_reshape_super':
super-intel.c:8665:7: error: 'devnum' may be used uninitialized in this function [-Werror=uninitialized]

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>