Fix warning: comparison between signed and unsigned integer expressions
Fix warning: comparison between signed and unsigned integer expressions

* Fix this:
simc_lsmplugin.c:2312:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] <--[gcc]
         for (i = 0; i < pd->num_systems; ++i) {
                       ^

Signed-off-by: Gris Ge <e24f3acbe39bf94f92e8af3c48f8852106ad5ad7@redhat.com>

cathay4t/libstoragemgmt,libstorage/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,tasleson/libstoragemgmt,libstorage/libstoragemgmt,tasleson/libstoragemgmt,jumitche/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,tasleson/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,libstorage/libstoragemgmt,joehandzik/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,joehandzik/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt