fix(st-clock): use Boolean type for tests

This corrects MISRA C2012-14.4
The controlling expression of an if statement and the controlling
expression of an iteration-statement shall have essentially Boolean type.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Id217d3da223caf75cd0439d7ce11c9efab87b4d2
diff --git a/drivers/st/clk/clk-stm32-core.c b/drivers/st/clk/clk-stm32-core.c
index bb03125..d166d54 100644
--- a/drivers/st/clk/clk-stm32-core.c
+++ b/drivers/st/clk/clk-stm32-core.c
@@ -519,7 +519,7 @@
 
 bool _stm32_clk_is_flags(struct stm32_clk_priv *priv, int id, uint8_t flag)
 {
-	if (_stm32_clk_get_flags(priv, id) & flag) {
+	if ((_stm32_clk_get_flags(priv, id) & flag) != 0U) {
 		return true;
 	}
 
@@ -549,7 +549,7 @@
 		}
 		if (parent != CLK_IS_ROOT) {
 			ret = _clk_stm32_enable_core(priv, parent);
-			if (ret) {
+			if (ret != 0) {
 				return ret;
 			}
 		}