rx and tx are of type int instead of bit field now

Signed-off-by: Christina Quast <chrysh.ng+github@gmail.com>
Code refactoring: static functions

Made functions in drbcc_packet.c static
Deleted unused functions for sync and ack buffer creation

Signed-off-by: Christina Quast <chrysh.ng+github@gmail.com>
Editted module description

Signed-off-by: Christina Quast <chrysh.ng+github@gmail.com>
Code refactoring in header files

Renamed macros to more intuitively understandable names
Moved global request-response mapping table to drbbc-core-only header
Removed usage of semaphores in drbcc_rtc

Signed-off-by: Christina Quast <chrysh.ng+github@gmail.com>
Code refactoring in drbcc core

Function definitions and defines moved to header
Private variables in drbcc_core.c declared static
Deleted unused includes

Signed-off-by: Christina Quast <chrysh.ng+github@gmail.com>