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: NMasahiro Yamada <yamada.masahiro@socionext.com>