ARM: OMAP2+: Allocate struct omap_hwmod based on dts data

With ti-sysc interconnect target module, we can allocate struct omap_hwmod
data based on the devicetree data. This allows dropping the static SoC
specific data eventually so we will only boot with data we actually need.

To allocate struct omap_hwmod dynamically, we need to add a mutex for
modifying the list, and remove __init for few functions.

Note that we are not initialized oh->_clk or the optional clocks and their
related quirks. That can be directly handled by the interconnect target
module driver.

Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>