qga: Fix memory allocation pasto

qmp_guest_file_seek() allocates memory for a GuestFileRead object
instead of the GuestFileSeek object it actually uses.  Harmless,
because the GuestFileRead is slightly larger.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

qga/commands-posix.c

@@ -534,7 +534,7 @@ struct GuestFileSeek *qmp_guest_file_seek(int64_t handle, int64_t offset,
     if (ret == -1) {
         error_setg_errno(err, errno, "failed to seek file");
     } else {
-        seek_data = g_malloc0(sizeof(GuestFileRead));
+        seek_data = g_new0(GuestFileSeek, 1);
         seek_data->position = ftell(fh);
         seek_data->eof = feof(fh);
     }