i5100_edac: Fix a warning when compiled with 32 bits

drivers/edac/i5100_edac.c: In function ‘i5100_init_csrows’:
drivers/edac/i5100_edac.c:862:3: warning: format ‘%zd’ expects argument of type ‘signed size_t’, but argument 5 has type ‘long unsigned int’ [-Wformat]

Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Cc: "Niklas Söderlund" <niklas.soderlund@ericsson.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>