staging: wilc1000: fix warning while printing

size_t should print using %zu and unsigned long int should use %lu
but here it was using %d and hence we were getting warning while
printing.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>