MIPS: TXx9: Update rbtx49xx_defconfig
Enable following features:
* MTD (RBTX4939, NAND_TXX9NDFMC)
* HW_RANDOM (HW_RANDOM_TX4939)
* SOUND (SND_SOC_TXX9ACLC)
* DMADEVICE (TXX9_DMAC)
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>