arm, powerpc: select SYS_GENERIC_BOARD

We have finished Generic Board conversion for ARM and PowerPC, i.e.
all the boards have been converted except OpenRISC, SuperH, SPARC,
which have not supported Generic Board framework yet.

Select SYS_GENERIC_BOARD in arch/Kconfig and delete all the macro
defines in include/configs/*.h.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/Kconfig

@@ -24,6 +24,7 @@ config ARM
 	select CREATE_ARCH_SYMLINK
 	select HAVE_PRIVATE_LIBGCC if !ARM64
 	select HAVE_GENERIC_BOARD
+	select SYS_GENERIC_BOARD
 	select SUPPORT_OF_CONTROL
 
 config AVR32
@@ -75,6 +76,7 @@ config PPC
 	bool "PowerPC architecture"
 	select HAVE_PRIVATE_LIBGCC
 	select HAVE_GENERIC_BOARD
+	select SYS_GENERIC_BOARD
 	select SUPPORT_OF_CONTROL
 
 config SANDBOX