target-mips: fix 34Kf configuration for DSP ASE

34Kf core does support DSP ASE.
CP0_Config3 configuration for 34Kf and description are wrong.

Please refer to MIPS32(R) 34Kf(TM) Processor Core Datasheet

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>