ARM: 8348/1: remove comments on CPU_ARM1020_CPU_IDLE

CPU_ARM1020_CPU_IDLE is not defined in Kconfig.  The last reference on
LKML dates back to 2001, so we can safely remove the comments to make
static analysis tools happy.

Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>