omap2: add OMAP24XX Power/Reset Management register defines

omap2: add OMAP24XX Power/Reset Management register defines

Add symbolic constants for OMAP24XX Power/Reset Management registers,
along with read/write functions.  The registers are divided into two
groups: global registers and module registers.  Global registers appear
only once on the chip, and are used with prm_{read,write}_reg().  Module
registers generally appear more than once, in different OMAP modules,
and have similar functions in each module.  They are used with
prm_{read,write}_mod_reg().

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>