arch: arm: clean up inclusions in assembly files

A clean-up commit that removes unnecessary inclusions from
assembly files in arm/core and arm/core/cortex_m. It also
ogranizes the inclusions based on the following order and
set of rules:
- never include kernel_structs.h
- include toolchain.h and linker/sections.h in all ASM files
- include offsets-short.h, if ASM accesses offset constants
- include arch/cpu.h, if ASM accesses CMSIS constants
  (defined locally in include/arch/arm)
- include file-specific headers, if needed (e.g. vector-table.h)

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

arch/arm/core/cpu_idle.S

@@ -10,13 +10,8 @@
  *
  */
 
-#include <offsets_short.h>
 #include <toolchain.h>
 #include <linker/sections.h>
-#include <arch/cpu.h>
-#ifdef CONFIG_TICKLESS_IDLE
-#include <kernel_structs.h>
-#endif
 
 _ASM_FILE_PROLOGUE
 

arch/arm/core/exc_exit.S

@@ -14,9 +14,9 @@
  * wrapped around by _isr_wrapper()).
  */
 
-#include <kernel_structs.h>
-#include <offsets_short.h>
 #include <toolchain.h>
+#include <linker/sections.h>
+#include <offsets_short.h>
 #include <arch/cpu.h>
 
 _ASM_FILE_PROLOGUE

arch/arm/core/isr_wrapper.S

@@ -12,12 +12,12 @@
  * a parameter.
  */
 
-#include <offsets_short.h>
 #include <toolchain.h>
 #include <linker/sections.h>
-#include <sw_isr_table.h>
-#include <kernel_structs.h>
+#include <offsets_short.h>
 #include <arch/cpu.h>
+#include <sw_isr_table.h>
+
 
 _ASM_FILE_PROLOGUE
 

arch/arm/core/swap_helper.S

@@ -12,9 +12,9 @@
  * on ARM Cortex-M CPUs.
  */
 
-#include <kernel_structs.h>
-#include <offsets_short.h>
 #include <toolchain.h>
+#include <linker/sections.h>
+#include <offsets_short.h>
 #include <arch/cpu.h>
 #include <syscall.h>
 

arch/arm/core/userspace.S

@@ -7,11 +7,9 @@
  *
  */
 
-#include <offsets_short.h>
 #include <toolchain.h>
 #include <linker/sections.h>
-#include <kernel_structs.h>
-#include <arch/cpu.h>
+#include <offsets_short.h>
 #include <syscall.h>
 
 _ASM_FILE_PROLOGUE