platform/mellanox: mlxbf-pmc: fix signedness bugs

These need to be signed for the error handling to work.  The
mlxbf_pmc_get_event_num() function returns int so int type is correct.

Fixes: 1ae9ffd ("platform/mellanox: mlxbf-pmc: Cleanup signed/unsigned mix-up")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/a4af764e-990b-4ebd-b342-852844374032@moroto.mountain
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/mellanox/mlxbf-pmc.c

@@ -1505,8 +1505,9 @@ static ssize_t mlxbf_pmc_counter_show(struct device *dev,
 {
 	struct mlxbf_pmc_attribute *attr_counter = container_of(
 		attr, struct mlxbf_pmc_attribute, dev_attr);
-	unsigned int blk_num, cnt_num, offset;
+	unsigned int blk_num, cnt_num;
 	bool is_l3 = false;
+	int offset;
 	u64 value;
 
 	blk_num = attr_counter->nr;
@@ -1539,9 +1540,10 @@ static ssize_t mlxbf_pmc_counter_store(struct device *dev,
 {
 	struct mlxbf_pmc_attribute *attr_counter = container_of(
 		attr, struct mlxbf_pmc_attribute, dev_attr);
-	unsigned int blk_num, cnt_num, offset, data;
+	unsigned int blk_num, cnt_num, data;
 	bool is_l3 = false;
 	u64 evt_num;
+	int offset;
 	int err;
 
 	blk_num = attr_counter->nr;
@@ -1621,8 +1623,9 @@ static ssize_t mlxbf_pmc_event_store(struct device *dev,
 {
 	struct mlxbf_pmc_attribute *attr_event = container_of(
 		attr, struct mlxbf_pmc_attribute, dev_attr);
-	unsigned int blk_num, cnt_num, evt_num;
+	unsigned int blk_num, cnt_num;
 	bool is_l3 = false;
+	int evt_num;
 	int err;
 
 	blk_num = attr_event->nr;