pcu_utils.h: Replace software based bitcount impl with gcc builtin

The cast for different types it's not really needed, simply use the
unsigned long long version to make sure we don't drop 1s, in any case
__builtin_popcountll() will be quicker than what we used to have.

Change-Id: I80ae72d34d53564fc3da1601ee48c8b2ffe79735
---
M src/pcu_utils.h
1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/pcu_utils.h b/src/pcu_utils.h
index a6beab0..0be37e9 100644
--- a/src/pcu_utils.h
+++ b/src/pcu_utils.h
@@ -67,17 +67,10 @@
 	return fn % GSM_MAX_FN;
 }
 
-#ifdef __cplusplus
-template <typename T>
-inline unsigned int pcu_bitcount(T x)
+inline unsigned int pcu_bitcount(unsigned long long x)
 {
-	unsigned int count = 0;
-	for (count = 0; x; count += 1)
-		x &= x - 1;
-
-	return count;
+	return __builtin_popcountll(x);
 }
-#endif
 
 static inline uint8_t pcu_lsb(uint8_t x)
 {

