intel: Refactor common platform code [1/5]

Pull out handoff driver to intel/soc/ common directory as they can be
shared by both Agilex and Stratix10 platform.

Share platform_def header between both Agilex and Stratix10 and store
platform specific definitions in socfpga_plat_def.h

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I8eff1afd7ee71704a36a54fad732ede4f557878d
diff --git a/plat/intel/soc/stratix10/bl2_plat_setup.c b/plat/intel/soc/stratix10/bl2_plat_setup.c
index f24bbde..cc6b4a7 100644
--- a/plat/intel/soc/stratix10/bl2_plat_setup.c
+++ b/plat/intel/soc/stratix10/bl2_plat_setup.c
@@ -27,11 +27,11 @@
 #include "s10_memory_controller.h"
 #include "s10_reset_manager.h"
 #include "s10_clock_manager.h"
-#include "s10_handoff.h"
 #include "s10_pinmux.h"
 #include "stratix10_private.h"
 #include "include/s10_mailbox.h"
 #include "qspi/cadence_qspi.h"
+#include "socfpga_handoff.h"
 #include "wdt/watchdog.h"
 
 
@@ -63,7 +63,7 @@
 
 	generic_delay_timer_init();
 
-	if (s10_get_handoff(&reverse_handoff_ptr))
+	if (socfpga_get_handoff(&reverse_handoff_ptr))
 		return;
 	config_pinmux(&reverse_handoff_ptr);
 	boot_source = reverse_handoff_ptr.boot_source;