codafs: fix build break when CONFIG_PROC_SYSCTL=n

Commit 0bc825d240ab ("codafs: fix compile warning when CONFIG_SYSCTL=n")
introduces build breakage, when CONFIG_PROC_SYSCTL=n and
CONFIG_CODA_FS=y:

fs/built-in.o: In function `init_coda':
psdev.c:(.init.text+0xc02): undefined reference to `coda_sysctl_init'
psdev.c:(.init.text+0xc7c): undefined reference to `coda_sysctl_clean'
fs/built-in.o: In function `exit_coda':
psdev.c:(.exit.text+0xa9): undefined reference to `coda_sysctl_clean'
make: *** [.tmp_vmlinux1] Error 1

Signed-off-by: Rakib Mullick <[e-mail]>
Reported-by: Ingo Molnar <[e-mail]>
Acked-by: Randy Dunlap <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/coda/sysctl.c

···
 		fs_table_header = NULL;
 	}
 }
+
+#else
+void coda_sysctl_init(void)
+{
+}
+
+void coda_sysctl_clean(void)
+{
+}
 #endif