ECMD-PDBG : Enable Scom support for all the targets

[lkammath]

ECMD work split up:

• Modify the ecmd-pdbg internal table ->Use pdbg_target_path() to select path from the device tree
  ->Use pdbg_address_absolute() to get the absolute address instead of existing hardcoded logic which takes Processor chip as default (https://github.com/open-power/ecmd-pdbg/blob/master/src/dll/edbgEcmdDll.C#L1085)

Optional work:

• ECMD_PDBG to get rid of its local device tree manipulation/handling and depend on PDBG to do it
• Instead of doing mmap -> https://github.com/open-power/ecmd-pdbg/blob/master/src/dll/edbgEcmdDll.C#L278 replace it with -- the whole function should just call pdbg_targets_init(NULL) and be done with it -- We might also want to call pdbg_set_backend()

Test vehicle: P9 or P10

[ojayanth]

Sizing includes testing effort. Code impact is minimal.

[lkammath]

https://github.com/open-power/ecmd-pdbg/pull/49 - Closed https://github.ibm.com/phal/ecmd-pdbg/pull/2/ - Under review

Tested on p9 and p10

Included the option work as well

[lkammath]

Both integrated to respective ecmd-pdbg repo. can be marked closed once available in the 1020 build