Bluetooth: bcm203x: remove superfluous header files

bcm203x.c hasn't use any macro or function declared in linux/atomic.h.
Thus, these files can be removed from bcm203x.c safely without
affecting the compilation of the ./drivers/bluetooth module

Signed-off-by: Mianhan Liu <liumh1@shanghaitech.edu.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>