ARM: OMAP2+: PRM: add generic API for checking hardreset status

PRM driver now has a generic API for checking hardreset status. SoC
specific support functions are registered through the prm_ll_data.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>