Patch from Andrew Zabolotny

This patch makes architecture-specific submenus under
"System Type" visible only if the corresponding architecture
is selected via the "ARM System Type" menu. Also comments
out IDE_POLL in mach-lh7a40x/Kconfig since it is undefined
and causes warnings during make menuconfig.
Signed-off-by: Andrew Zabolotny <zap@homelink.ru>