lib: utils_def: add CLAMP macro

Add the standard CLAMP macro.  It ensures that
x is between the limits set by low and high.
If low is greater than high the result is undefined.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: Ia173bb9ca51bc8d9a8ec573bbc15636a94f881f4

include/lib/utils_def.h

@@ -77,6 +77,15 @@
 	_x > _y ? _x : _y;		\
 })
 
+#define CLAMP(x, min, max) __extension__ ({ \
+	__typeof__(x) _x = (x); \
+	__typeof__(min) _min = (min); \
+	__typeof__(max) _max = (max); \
+	(void)(&_x == &_min); \
+	(void)(&_x == &_max); \
+	(_x > _max ? _max : (_x < _min ? _min : _x)); \
+})
+
 /*
  * The round_up() macro rounds up a value to the given boundary in a
  * type-agnostic yet type-safe manner. The boundary must be a power of two.