powerpc: Kconfig: remove BE-only platforms from LE kernel build

Currently, little endian is only supported on powernv and pseries,
however, Kconfigs still allow us to include other platforms in a LE
kernel, this may result in space wasting or even build error if some
BE-only platforms always assume they are built for a BE kernel. So just
modify the Kconfigs of BE-only platforms to remove them from being built
for a LE kernel.

For 32bit only platforms, nothing needs to be done, because
CPU_LITTLE_ENDIAN depends on PPC64. For 64bit supported platforms, add
CPU_BIG_ENDIAN to dependencies explicitly, so that these platforms will
be disabled for LE [Suggested-by: Cédric Le Goater <clg@fr.ibm.com>].
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/cell/Kconfig

@@ -25,7 +25,7 @@ config PPC_CELL_NATIVE
 
 config PPC_IBM_CELL_BLADE
 	bool "IBM Cell Blade"
-	depends on PPC64 && PPC_BOOK3S
+	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
 	select PPC_CELL_NATIVE
 	select PPC_OF_PLATFORM_PCI
 	select PCI
@@ -35,7 +35,7 @@ config PPC_IBM_CELL_BLADE
 
 config PPC_CELL_QPACE
 	bool "IBM Cell - QPACE"
-	depends on PPC64 && PPC_BOOK3S
+	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
 	select PPC_CELL_COMMON
 
 config AXON_MSI

arch/powerpc/platforms/maple/Kconfig

 config PPC_MAPLE
-	depends on PPC64 && PPC_BOOK3S
+	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
 	bool "Maple 970FX Evaluation Board"
 	select PCI
 	select MPIC

arch/powerpc/platforms/pasemi/Kconfig

 config PPC_PASEMI
-	depends on PPC64 && PPC_BOOK3S
+	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
 	bool "PA Semi SoC-based platforms"
 	default n
 	select MPIC

arch/powerpc/platforms/powermac/Kconfig

 config PPC_PMAC
 	bool "Apple PowerMac based machines"
-	depends on PPC_BOOK3S
+	depends on PPC_BOOK3S && CPU_BIG_ENDIAN
 	select MPIC
 	select PCI
 	select PPC_INDIRECT_PCI if PPC32

arch/powerpc/platforms/ps3/Kconfig

 config PPC_PS3
 	bool "Sony PS3"
-	depends on PPC64 && PPC_BOOK3S
+	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
 	select PPC_CELL
 	select USB_OHCI_LITTLE_ENDIAN
 	select USB_OHCI_BIG_ENDIAN_MMIO