board: thead: Remove <common.h> and add needed includes

Remove <common.h> from this board vendor directory and when needed
add missing include files directly.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/thead/th1520_lpi4a/board.c b/board/thead/th1520_lpi4a/board.c
index 16c3e45..bb83e75 100644
--- a/board/thead/th1520_lpi4a/board.c
+++ b/board/thead/th1520_lpi4a/board.c
@@ -4,7 +4,6 @@
  *
  */
 
-#include <common.h>
 #include <cpu_func.h>
 
 int board_init(void)