proc: move /proc/interrupts boilerplate code to fs/proc/interrupts.c

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 13ffa7b..b921f44 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -12,6 +12,7 @@
 proc-y	+= cmdline.o
 proc-y	+= cpuinfo.o
 proc-y	+= devices.o
+proc-y	+= interrupts.o
 proc-y	+= loadavg.o
 proc-y	+= meminfo.o
 proc-y	+= stat.o