Merge rbhma4200(RBTX4927/37) and rbhma4500(RBTX4938) defconfig into
single rbtx49xx defconfig.  And jmr3927 defconfig is also updated.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>