audio: fix multi-codec conf issue

audio: fix multi-codec conf issue

PD#147919: ksize() doesn't return the alloc memory size.
Use card saved num_confs to calc the actual old size.

'amixer controls' will be:
...
numid=10,iface=MIXER,name='3101_B PGA Level Volume'
numid=45,iface=MIXER,name='3101_B Right Input Mixer IN1_R P Switch'
numid=46,iface=MIXER,name='3101_B Right Input Mixer IN2_R P Switch'
numid=47,iface=MIXER,name='3101_B Right Input Mixer IN3_R P Switch'
numid=26,iface=MIXER,name='5707_A Ch1 Switch'
numid=24,iface=MIXER,name='5707_A Ch1 Volume'
numid=27,iface=MIXER,name='5707_A Ch2 Switch'
numid=25,iface=MIXER,name='5707_A Ch2 Volume'
numid=28,iface=MIXER,name='5707_A Fine Master Volume'
numid=23,iface=MIXER,name='5707_A Master Volume'
numid=30,iface=MIXER,name='5707_A Set DRC Enable'
numid=29,iface=MIXER,name='5707_A Set EQ Enable'
numid=34,iface=MIXER,name='5707_B Ch1 Switch'
numid=32,iface=MIXER,name='5707_B Ch1 Volume'
numid=35,iface=MIXER,name='5707_B Ch2 Switch'
numid=33,iface=MIXER,name='5707_B Ch2 Volume'
numid=36,iface=MIXER,name='5707_B Fine Master Volume'
numid=31,iface=MIXER,name='5707_B Master Volume'
numid=38,iface=MIXER,name='5707_B Set DRC Enable'
numid=37,iface=MIXER,name='5707_B Set EQ Enable'

Change-Id: I8e7d977b523c63ee1bb5ce1284892893db34f2f2
Signed-off-by: Shuai Li <shuai.li@amlogic.com>