nios2: remove unnecessary header include path

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Thomas Chou <thomas@wytron.com.tw>
diff --git a/board/altera/nios2-generic/config.mk b/board/altera/nios2-generic/config.mk
index f9f317c..a673525 100644
--- a/board/altera/nios2-generic/config.mk
+++ b/board/altera/nios2-generic/config.mk
@@ -5,11 +5,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-# we get text_base from board config header, so do not use this
-#CONFIG_SYS_TEXT_BASE = do-not-use-me
-
 PLATFORM_CPPFLAGS += -mno-hw-div -mno-hw-mul
-PLATFORM_CPPFLAGS += -I$(TOPDIR)/board/$(VENDOR)/include
 
 ifeq ($(debug),1)
 PLATFORM_CPPFLAGS += -DDEBUG
diff --git a/board/psyent/pci5441/config.mk b/board/psyent/pci5441/config.mk
index 00ff743..776fa8a 100644
--- a/board/psyent/pci5441/config.mk
+++ b/board/psyent/pci5441/config.mk
@@ -8,7 +8,6 @@
 CONFIG_SYS_TEXT_BASE = 0x018e0000
 
 PLATFORM_CPPFLAGS += -mno-hw-div -mno-hw-mul
-PLATFORM_CPPFLAGS += -I$(TOPDIR)/board/$(VENDOR)/include
 
 ifeq ($(debug),1)
 PLATFORM_CPPFLAGS += -DDEBUG
diff --git a/board/psyent/pk1c20/config.mk b/board/psyent/pk1c20/config.mk
index 7b0810a..83cfadc 100644
--- a/board/psyent/pk1c20/config.mk
+++ b/board/psyent/pk1c20/config.mk
@@ -8,7 +8,6 @@
 CONFIG_SYS_TEXT_BASE = 0x01fc0000
 
 PLATFORM_CPPFLAGS += -mno-hw-div -mno-hw-mul
-PLATFORM_CPPFLAGS += -I$(TOPDIR)/board/$(VENDOR)/include
 
 ifeq ($(debug),1)
 PLATFORM_CPPFLAGS += -DDEBUG