musb_hdrc, CamelCase begone (rest of CPPI)

This should be the last of the CamelCase removal for CPPI...
more local variable updates:

 - "txState" --> tx_ram
 - "bReqComplete" --> complete (or remove)
 - "bdPtr" --> bd
 - "chanNum" --> index
 - remove pointless/unused "numCompleted"
 - convert cppi_rx_scan() to use bool, return true/false

Also improve indentation on the monstrous TX side of cppi_completion();
TX paths still deserve a rewrite to better match the RX side.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>