staging: vme_user: Fix possible UAF in tsi148_dma_list_add

In the Linux kernel, the following vulnerability has been resolved:

staging: vme_user: Fix possible UAF in tsi148_dma_list_add

Smatch report warning as follows:

drivers/staging/vme_user/vme_tsi148.c:1757 tsi148_dma_list_add() warn:
'&entry->list' not removed from list

In tsi148_dma_list_add(), the error path "goto err_dma" will not
remove entry->list from list->entries, but entry will be freed,
then list traversal may cause UAF.

Fix by removeing it from list->entries before free().