arch: arc: Fixed an error in include-guard

Fixed definitions duplicated with those in
`include/zephyr/arch/xtensa/arch_inlines.h`.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>

include/zephyr/arch/arc/arch_inlines.h

@@ -5,8 +5,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#ifndef ZEPHYR_INCLUDE_ARCH_XTENSA_ARCH_INLINES_H_
-#define ZEPHYR_INCLUDE_ARCH_XTENSA_ARCH_INLINES_H_
+#ifndef ZEPHYR_INCLUDE_ARCH_ARC_ARCH_INLINES_H_
+#define ZEPHYR_INCLUDE_ARCH_ARC_ARCH_INLINES_H_
 
 #ifndef _ASMLANGUAGE
 
@@ -42,4 +42,4 @@ static ALWAYS_INLINE unsigned int arch_num_cpus(void)
 }
 
 #endif /* !_ASMLANGUAGE */
-#endif /* ZEPHYR_INCLUDE_ARCH_XTENSA_ARCH_INLINES_H_ */
+#endif /* ZEPHYR_INCLUDE_ARCH_ARC_ARCH_INLINES_H_ */