qcacld: support for additional powersave modes

currently there are only two valid values for gEnablePowerSaveOffload.
0 - Disable Powersave Offload
1 - Enable Powersave Offload

But additional powersave modes are required in powersave offload case
for rome.

So gEnablePowerSaveOffload is extended to support additional modes.

a) gEnablePowerSaveOffload = 0
   Powersave Offload is disabled.

b) gEnablePowerSaveOffload = 1
   Powersave offload enabled : Legacy Powersave + Deepsleep mode disabled

c) gEnablePowerSaveOffload = 2
   Powersave offload enabled : QPower + Deepsleep mode disabled

d) gEnablePowerSaveOffload = 3
   Powersave offload enabled : Legacy Powersave + Deepsleep mode enabled

e) gEnablePowerSaveOffload = 4
   Powersave offload enabled : QPower + Deepsleep mode enabled

Change-Id: I195ed519b69a23d4f4cb1b8d65dcb79915da7599
CRs-Fixed: 570158