intel: s10: Remove unused source code

remove plat_sip_svc.c and plat_psci.c in stratix 10 platform directory
as both has been refactored to common directory for sharing with agilex
platform

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I395fed66408f536e8fefd637681e742c63621818
2 files changed