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]