feat(versal): add SMCCC call TF_A_PM_REGISTER_SGI

This call is used to register and reset SGI interrupt.
Before this functionality was performed using IOCTL_REGISTER_SGI
pm_ioctl EEMI call. It's not correct use of PM_IOCTL as it is
not EEMI functionality. Instead this new SMCCC call will be
handled by TF-A specific handler.

Change-Id: If2408af38b889d29a5c584e8eec5f1672eab4fb5
Signed-off-by: Tanmay Shah <tanmay.shah@xilinx.com>