hwspinlock: stm32: migrate trace to log macro

Define LOG_CATEGORY to allow filtering with log command.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/hwspinlock/stm32_hwspinlock.c b/drivers/hwspinlock/stm32_hwspinlock.c
index fdc1f6f..46ed646 100644
--- a/drivers/hwspinlock/stm32_hwspinlock.c
+++ b/drivers/hwspinlock/stm32_hwspinlock.c
@@ -3,6 +3,8 @@
  * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
  */
 
+#define LOG_CATEGORY UCLASS_HWSPINLOCK
+
 #include <common.h>
 #include <clk.h>
 #include <dm.h>