ext/ldac: Fix typo in 88200(0) stereo encoder sampling rate

This explains why I was unable to encode stereo audio to 88200Hz. Strangely enough the "impossible" value shows up in gst-inspect-1.0 but not in the log line:

WARN                 ldacenc gstldacenc.c:210:gst_ldac_enc_do_negotiate:<ldac_enc> Couldn't negotiate output caps with input rate 88200 and input channels 2 and allowed output caps
audio/x-ldac, rate=(int){ 44100, 48000, 88200, 96000 }, channels=(int)1, channel-mode=(string)mono;
audio/x-ldac, rate=(int){ 44100, 48000, 96000 }, channels=(int)2, channel-mode=(string){ dual, stereo }

Fixes: a5768145 ("ext: Add LDAC encoder")

CC @SanchayanMaity