net/mrvl: reset errno before library call

In case errno contains some non-zero value and call to strtoul() is
successful -2 error will be returned.

Setting errno to zero before calling strtoul() makes sure
errors will be handled correctly.

Fixes: 0ddc9b815b ("net/mrvl: add net PMD skeleton")

Signed-off-by: Tomasz Duszynski <tdu@semihalf.com>

drivers/net/mrvl/mrvl_qos.c

@@ -99,6 +99,7 @@ get_val_securely(const char *string, uint32_t *val)
 	if (len == 0)
 		return -1;
 
+	errno = 0;
 	*val = strtoul(string, &endptr, 0);
 	if (errno != 0 || RTE_PTR_DIFF(endptr, string) != len)
 		return -2;