MIPS: Malta: add suspend state entry code

This patch introduces code which will enter a suspend state via the
PIIX4. This can only be done when PCI support is enabled since it
requires access to PCI I/O space and the generation of a special cycle
on the PCI bus. In cases where PCI is disabled the mips_pm_suspend
function will simply always return an error.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6905/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 4e49591..2f2020f 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1671,6 +1671,12 @@
 config SYS_HAS_CPU_XLP
 	bool
 
+config MIPS_MALTA_PM
+	depends on MIPS_MALTA
+	depends on PCI
+	bool
+	default y
+
 #
 # CPU may reorder R->R, R->W, W->R, W->W
 # Reordering beyond LL and SC is handled in WEAK_REORDERING_BEYOND_LLSC