Revert "Add support for IAR Compiler"

This reverts commit ead24644f008232f81e0408bfb15e99deff115bb.

include/rtthread.h

@@ -571,7 +571,7 @@ void rt_components_board_init(void);
 #define rt_kputs(str)
 #else
 #if defined(__ARMCC_VERSION) || defined(__GNUC__) || \
-    defined(__ICCARM__) || defined(__TI_COMPILER_VERSION__)
+    defined(__TI_COMPILER_VERSION__)
 int rt_kprintf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
 #else
 int rt_kprintf(const char *fmt, ...);