ia64: prefix header search path with $(srctree)/

Currently, the Kbuild core manipulates header search paths in a crazy
way [1].

To fix this mess, I want all Makefiles to add explicit $(srctree)/ to
the search paths in the srctree. Some Makefiles are already written in
that way, but not all. The goal of this work is to make the notation
consistent, and finally get rid of the gross hacks.

Having whitespaces after -I does not matter since commit 48f6e3cf
("kbuild: do not drop -I without parameter").

I removed some header search paths because I was able to build ia64
without them.

[1]: https://patchwork.kernel.org/patch/9632347/Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

arch/ia64/sn/kernel/Makefile

@@ -7,7 +7,7 @@
 # Copyright (C) 1999,2001-2006,2008 Silicon Graphics, Inc.  All Rights Reserved.
 #
 
-ccflags-y := -Iarch/ia64/sn/include
+ccflags-y := -I $(srctree)/arch/ia64/sn/include
 
 obj-y				+= setup.o bte.o bte_error.o irq.o mca.o idle.o \
 				   huberror.o io_acpi_init.o io_common.o \

arch/ia64/sn/kernel/sn2/Makefile

@@ -9,7 +9,5 @@
 # sn2 specific kernel files
 #
 
-ccflags-y := -Iarch/ia64/sn/include
-
 obj-y += cache.o io.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o \
 	 prominfo_proc.o timer.o timer_interrupt.o sn_hwperf.o

arch/ia64/sn/pci/Makefile

@@ -7,6 +7,4 @@
 #
 # Makefile for the sn pci general routines.
 
-ccflags-y := -Iarch/ia64/sn/include
-
 obj-y := pci_dma.o tioca_provider.o tioce_provider.o pcibr/

arch/ia64/sn/pci/pcibr/Makefile

@@ -7,7 +7,7 @@
 #
 # Makefile for the sn2 io routines.
 
-ccflags-y := -Iarch/ia64/sn/include
+ccflags-y := -I $(srctree)/arch/ia64/sn/include
 
 obj-y				+=  pcibr_dma.o pcibr_reg.o \
 				    pcibr_ate.o pcibr_provider.o