selftests/ir: remove ARRAY_SIZE define from ir_loopback.c

ARRAY_SIZE is defined in several selftests. Remove definitions from
individual test files and include header file for the define instead.
ARRAY_SIZE define is added in a separate patch to prepare for this
change.

Remove ARRAY_SIZE from ir_loopback.c and pickup the one defined
in kselftest.h.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: shuahkh

tools/testing/selftests/ir/ir_loopback.c

@@ -26,7 +26,6 @@
 #include "../kselftest.h"
 
 #define TEST_SCANCODES	10
-#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 #define SYSFS_PATH_MAX 256
 #define DNAME_PATH_MAX 256