blackfin:Use generic /proc/interrupts implementation

There is nothing special in that blackfin code. Use the core
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Miao <realmz6@gmail.com>
Cc: bfin <adi-buildroot-devel@lists.sourceforge.net>

diff --cc arch/blackfin/Kconfig
Simple merge

diff --cc arch/blackfin/kernel/irqchip.c
Simple merge