OMAP2+: PM: fix section mismatch in pm_dbg_init()

Fix the section mismatch warning:

  WARNING: vmlinux.o(.text+0x21118): Section mismatch
  in reference from the function pm_dbg_init() to the
  function .init.text:pwrdms_setup()
  The function pm_dbg_init() references
  the function __init pwrdms_setup().
  This is often because pm_dbg_init lacks a __init
  annotation or the annotation of pwrdms_setup is wrong.

Signed-off-by: Sanjeev Premi <premi@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>