helper: Remove src/helper from include dirs

The header files under src/helper/ can currently be included with
either

    #include <bits.h>
    or
    #include <helper/bits.h>

This is because we specify both "src/" and "src/helper/" directories
as include directories.  Some files name under "src/helper/", such as
types.h, log.h, and util.h are too generic and could be ambiguous
depending on the search path.

This commit remove "src/helper/" from our include dir and make C files
include explicitly.

Change-Id: I38fc9b96ba01a513d4a72757d40007e21b502f25
Signed-off-by: Yasushi SHOJI <yashi@spacecubics.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6507
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/flash/nor/psoc6.c

@@ -24,12 +24,12 @@
 #include <time.h>
 
 #include "imp.h"
-#include <target/arm_adi_v5.h>
+#include "helper/time_support.h"
+#include "target/arm_adi_v5.h"
 #include "target/target.h"
 #include "target/cortex_m.h"
 #include "target/breakpoints.h"
 #include "target/target_type.h"
-#include "time_support.h"
 #include "target/algorithm.h"
 
 /**************************************************************************************************

src/flash/nor/stm32l4x.c

@@ -26,10 +26,10 @@
 #include "imp.h"
 #include <helper/align.h>
 #include <helper/binarybuffer.h>
+#include <helper/bits.h>
 #include <target/algorithm.h>
 #include <target/arm_adi_v5.h>
 #include <target/cortex_m.h>
-#include "bits.h"
 #include "stm32l4x.h"
 
 /* STM32L4xxx series for reference.