ARM: OMAP2+: Allow using ti-sysc for system timers

If a system timer is configured with an interrconnect target module in
the dts, the ti,hwmods and module fck are at the interconnect target
level. Then there's a separate fck for the timer child device.

If the child device has a separate functional clock, we need to configure
it directly. For example, timer clk clkctrl clock bit 0 is the module
clock for the interconnect target, and bit 24 being the functional clock
for the timer IP.

For system timers, we already mark them as disabled. Now must also mark
the interconnect target module as disabled to prevent ti-sysc to manage
it instead of the system timer.

Cc: Keerthy <j-keerthy@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>