hal: Remove setting default values for slim_0_tx backend

DEFAULT_CODEC_TX_BACKEND & SLIMBUS_0_TX shares the
same enum, causing overriding of sample rate & format.

Remove setting of default values for SLIMBUS_0_TX sample
rate & format since it is already taken care as part of
DEFAULT_CODEC_TX_BACKEND

CRs-Fixed: 2529031
Change-Id: I180af115f05d49d34059eaf177cc4a4121744d0e
1 file changed