arm: remove wrong CONFIG_PROC_SYSCTL ifdef

The sysfs cpu_capacity entry for each CPU has nothing to do with
PROC_FS, nor it's in /proc/sys path.

Remove such ifdef.

Cc: Russell King <linux@arm.linux.org.uk>
Reported-and-suggested-by: Sudeep Holla <sudeep.holla@arm.com>
Fixes: 7e5930aa ('ARM: 8622/3: add sysfs cpu_capacity attribute')
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>