RDMA/erdma: Fix refcount leak in erdma_mmap

rdma_user_mmap_entry_get() take reference, we should release it when not
need anymore, add the missing rdma_user_mmap_entry_put() in the error
path to fix it.

Fixes: 15505577 ("RDMA/erdma: Add verbs implementation")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20221220121139.1540564-1-linmq006@gmail.comAcked-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/erdma/erdma_verbs.c

@@ -1110,12 +1110,14 @@ int erdma_mmap(struct ib_ucontext *ctx, struct vm_area_struct *vma)
 		prot = pgprot_device(vma->vm_page_prot);
 		break;
 	default:
-		return -EINVAL;
+		err = -EINVAL;
+		goto put_entry;
 	}
 
 	err = rdma_user_mmap_io(ctx, vma, PFN_DOWN(entry->address), PAGE_SIZE,
 				prot, rdma_entry);
 
+put_entry:
 	rdma_user_mmap_entry_put(rdma_entry);
 	return err;
 }