brcmfmac: rename dhd_cdc to bcdc

dhd_cdc is renamed to bcdc. This is a step in cleaning and
restructuring protocol layer. This is done so new protocols can
be added in the future. This step only renames the source files.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
[arend@broadcom.com: use 'git mv' to do the rename]
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>