ARM: PSCI: Rework the DT handler slightly

The way the PSCI DT update happens currently means we pull in
<asm/armv7.h> everywhere, including on ARMv8 and that in turn brings in
<asm/io.h> for some non-PSCI related things that header needs to deal
with.

To fix this, we rework the hook slightly.  A good portion of
arch/arm/cpu/armv7/virt-dt.c is common looking and I hope that when PSCI
is needed on ARMv8 we can re-use this by and large.  So rename the
current hook to psci_update_dt(), move the prototype to <asm/psci.h> and
add an #ifdef that will make re-use later easier.

Reported-by: York Sun <yorksun@freescale.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Ian Campbell <ijc@hellion.org.uk>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Signed-off-by: Tom Rini <trini@konsulko.com>
Acked-by: York Sun <yorksun@freescale.com>
diff --git a/arch/arm/lib/bootm-fdt.c b/arch/arm/lib/bootm-fdt.c
index d4f1578..665a3bc 100644
--- a/arch/arm/lib/bootm-fdt.c
+++ b/arch/arm/lib/bootm-fdt.c
@@ -17,7 +17,7 @@
 
 #include <common.h>
 #include <fdt_support.h>
-#include <asm/armv7.h>
+#include <asm/psci.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -38,7 +38,7 @@
 	if (ret)
 		return ret;
 
-	ret = armv7_update_dt(blob);
+	ret = psci_update_dt(blob);
 #endif
 	return ret;
 }