Make arch-specific linux.h include guards architecture unique

Replace uses of GRUB_LINUX_MACHINE_HEADER and GRUB_LINUX_CPU_HEADER
with GRUB_<arch>_LINUX_HEADER include guards to prevent issues when
including more than one of them.
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

include/grub/arm/linux.h

@@ -17,8 +17,8 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef GRUB_LINUX_CPU_HEADER
-#define GRUB_LINUX_CPU_HEADER 1
+#ifndef GRUB_ARM_LINUX_HEADER
+#define GRUB_ARM_LINUX_HEADER 1
 
 #define LINUX_ZIMAGE_OFFSET 0x24
 #define LINUX_ZIMAGE_MAGIC  0x016f2818
@@ -66,4 +66,4 @@ grub_arm_firmware_get_machine_type (void)
 
 #define FDT_ADDITIONAL_ENTRIES_SIZE	0x300
 
-#endif /* ! GRUB_LINUX_CPU_HEADER */
+#endif /* ! GRUB_ARM_LINUX_HEADER */

include/grub/arm64/linux.h

@@ -16,8 +16,8 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef GRUB_LINUX_CPU_HEADER
-#define GRUB_LINUX_CPU_HEADER 1
+#ifndef GRUB_ARM64_LINUX_HEADER
+#define GRUB_ARM64_LINUX_HEADER 1
 
 #include <grub/efi/efi.h>
 
@@ -43,4 +43,4 @@ grub_err_t grub_arm64_uefi_check_image (struct grub_arm64_linux_kernel_header
 grub_err_t grub_arm64_uefi_boot_image (grub_addr_t addr, grub_size_t size,
                                        char *args);
 
-#endif /* ! GRUB_LINUX_CPU_HEADER */
+#endif /* ! GRUB_ARM64_LINUX_HEADER */

include/grub/i386/linux.h

@@ -16,8 +16,8 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef GRUB_LINUX_MACHINE_HEADER
-#define GRUB_LINUX_MACHINE_HEADER	1
+#ifndef GRUB_I386_LINUX_HEADER
+#define GRUB_I386_LINUX_HEADER	1
 
 #define GRUB_LINUX_MAGIC_SIGNATURE	0x53726448      /* "HdrS" */
 #define GRUB_LINUX_DEFAULT_SETUP_SECTS	4
@@ -312,4 +312,4 @@ struct linux_kernel_params
 } GRUB_PACKED;
 #endif /* ! ASM_FILE */
 
-#endif /* ! GRUB_LINUX_MACHINE_HEADER */
+#endif /* ! GRUB_I386_LINUX_HEADER */