zynqmp: pm: Provide state argument to the pm_self_suspend API call

The state argument of the pm_self_suspend API encodes the state to
which the APU intends to suspend. The state can be:
- PM_APU_STATE_CPU_IDLE - processor power down, all memories remain
  on
- PM_APU_STATE_SUSPEND_TO_RAM - all processors powered down, L2$
  powered down, all OCM banks in retention and DDR in
  self-refresh.
The calls for setting requirements for L2$ and OCM banks are now
redundant and removed.

Signed-off-by: Filip Drazic <filip.drazic@aggios.com>
[ sb
 - remove redundant #defines
]
Signed-off-by: Sören Brinkmann <soren.brinkmann@xilinx.com>