ARM: simplify machdirs/platdirs handling

There is only one plat-* directory left, and the MACHINE variable is
only used for the mach/*.h header path.

Simplify this by removing the checks for ARCH_MULTIPLATFORM and
ARM_SINGLE_ARMV7M, and just adding the include directories for the
remaining three platforms manually.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/Makefile

@@ -224,40 +224,24 @@ machine-$(CONFIG_ARCH_ZYNQ)		+= zynq
 machine-$(CONFIG_PLAT_VERSATILE)	+= versatile
 machine-$(CONFIG_PLAT_SPEAR)		+= spear
 
-# Platform directory name.  This list is sorted alphanumerically
-# by CONFIG_* macro name.
-plat-$(CONFIG_PLAT_ORION)	+= orion
+# legacy platforms provide their own mach/*.h headers globally,
+# these three are mutually exclusive
+machdirs-$(CONFIG_ARCH_FOOTBRIDGE)	+= arch/arm/mach-footbridge
+machdirs-$(CONFIG_ARCH_RPC)		+= arch/arm/mach-rpc
+machdirs-$(CONFIG_ARCH_SA1100)		+= arch/arm/mach-sa1100
+KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%/include,$(machdirs-y))
 
 # The byte offset of the kernel image in RAM from the start of RAM.
 TEXT_OFFSET := $(textofs-y)
 
-# The first directory contains additional information for the boot setup code
-ifneq ($(machine-y),)
-MACHINE  := arch/arm/mach-$(word 1,$(machine-y))/
-else
-MACHINE  :=
-endif
-ifeq ($(CONFIG_ARCH_MULTIPLATFORM),y)
-MACHINE  :=
-endif
-
-machdirs := $(patsubst %,arch/arm/mach-%/,$(machine-y))
-platdirs := $(patsubst %,arch/arm/plat-%/,$(sort $(plat-y)))
-
-ifneq ($(CONFIG_ARCH_MULTIPLATFORM),y)
-ifneq ($(CONFIG_ARM_SINGLE_ARMV7M),y)
-KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(machdirs) $(platdirs))
-endif
-endif
-
 export	TEXT_OFFSET GZFLAGS MMUEXT
 
 # If we have a machine-specific directory, then include it in the build.
-core-y				+= $(machdirs) $(platdirs)
-
+core-y				+= $(patsubst %,arch/arm/mach-%/,$(machine-y))
 # For cleaning
-core-				+= $(patsubst %,arch/arm/mach-%/, $(machine-))
-core-				+= $(patsubst %,arch/arm/plat-%/, $(plat-))
+core-				+= $(patsubst %,arch/arm/mach-%/,$(machine-))
+
+core-$(CONFIG_PLAT_ORION)	+= arch/arm/plat-orion/
 
 libs-y				:= arch/arm/lib/ $(libs-y)