staging: silicom: remove BP_PROC_SUPPORT dependant code

Some code is hide inside #ifdef BP_PROC_SUPPORT and it never defined
anywhere. And, it made defined but not used function which calling
code was hide inside #ifdef BP_PROC_SUPPORT and caused following
build warning:

drivers/staging/silicom/bpctl_mod.c:6786:12: warning:
‘bp_proc_create’ defined but not used [-Wunused-function]
 static int bp_proc_create(void)
            ^

Fix the warning and remove code complexity by remove whole code
inside #ifdef BP_PROC_SUPPORT.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>