Disable preemption when accessing current cpu id

Currently Open CAS doesn't support kernels with involuntary preemption
anyways and once we add the support, we can get rid of this workaround

Signed-off-by: Michal Mielewczyk <michal.mielewczyk@huawei.com>

modules/cas_cache/utils/utils_rpool.c

@@ -1,6 +1,6 @@
 /*
 * Copyright(c) 2012-2022 Intel Corporation
-* Copyright(c) 2024 Huawei Technologies
+* Copyright(c) 2024-2025 Huawei Technologies
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
@@ -208,9 +208,13 @@ void *cas_rpool_try_get(struct cas_reserve_pool *rpool_master, int *cpu)
 
 	CAS_DEBUG_TRACE();
 
+	get_cpu();
+
 	*cpu = smp_processor_id();
 	current_rpool = &rpool_master->rpools[*cpu];
 
+	put_cpu();
+
 	spin_lock_irqsave(&current_rpool->lock, flags);
 
 	if (!list_empty(&current_rpool->list)) {