brcmfmac: Use dedicated trace level for CDC.

CDC debug is partly done with TRACE and partly with CTL, however
CDC hardly ever needs debugging. Use dedicated level CDC and
replace TRACE and CTL in dhd_cdc with that.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>