MIPS: TXx9: Add TX4939 SoC support

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

 create mode 100644 arch/mips/pci/pci-tx4939.c
 create mode 100644 arch/mips/txx9/generic/irq_tx4939.c
 create mode 100644 arch/mips/txx9/generic/setup_tx4939.c
 create mode 100644 include/asm-mips/txx9/tx4939.h