ARM: OMAP5: Cleanup options for SoC only build

OMAP5 SoC has Cortex-A15 which does not use TWD timer. It uses
ARCH_TIMER instead, clean up unwanted configuration and enable
OMAP_INTERCONNECT and OPP which is necessary for expected functionality
on the SoC.

Reported-by: Carlos Hernandez <ceh@ti.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>