arch, board: Add thumb support to i.MX6

Summary:
- This commit adds thumb support to i.MX6
- Also, applies the same coding style to arch_elf.c

Impact:
- i.MX6 only

Testing:
- Tested with sabre-6quad:smp (QEMU, Dev board)
- Tested with sabre-6quad:netnsh (QEMU)
- Tested with sabre-6quad:netknsh (QEMU, not merged yet)

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

arch/arm/Kconfig

@@ -80,6 +80,7 @@ config ARCH_CHIP_IMX1
 config ARCH_CHIP_IMX6
 	bool "NXP/Freescale iMX.6"
 	select ARCH_CORTEXA9
+	select ARM_THUMB
 	select ARMV7A_HAVE_L2CC_PL310
 	select ARCH_HAVE_FPU
 	select ARCH_HAVE_TRUSTZONE

boards/arm/imx6/sabre-6quad/scripts/Make.defs

@@ -34,7 +34,7 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCPUFLAGS = -mcpu=cortex-a9 -mfpu=vfpv4-d16
+ARCHCPUFLAGS = -mcpu=cortex-a9 -mfpu=vfpv4-d16 -mthumb
 ARCHCFLAGS = -fno-common -fno-builtin -ffunction-sections -fdata-sections
 ARCHCXXFLAGS = -fno-common -fno-builtin -fno-exceptions -fcheck-new -fno-rtti
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef

libs/libc/machine/arm/armv7-a/arch_elf.c

@@ -174,9 +174,9 @@ int up_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
         offset += sym->st_value - addr;
 
 #ifdef CONFIG_ARM_THUMB
-        if (offset & 2 || offset < (int32_t) 0xfe000000 ||
+        if ((offset & 2) != 0 || offset < (int32_t) 0xfe000000 ||
 #else
-        if (offset & 3 || offset < (int32_t) 0xfe000000 ||
+        if ((offset & 3) != 0 || offset < (int32_t) 0xfe000000 ||
 #endif
             offset >= (int32_t) 0x02000000)
           {