omap: hwmod: Handle modules with 16bit registers

Some modules which have 16bit registers can cause imprecise
aborts if a __raw_readl/writel is used to read/write 32 bits.

Add an additional flag to identify modules which have such
hard requirement, and handle it in the hwmod framework.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>