[ARM] pxa: better MFP low power state support for pxa25x/pxa27x

When configured as a specific low power state: MFP_LPM_DRIVE_LOW,
MFP_LPM_DRIVE_HIGH, the corresponding GPDR register bit during
low power mode shall be re-configured as output (if they are not
configured so), thus the PGSRx bits can output.

Create an additional low power values GPDR registers, and properly
save/restore the GAFR + GPDR registers when doing suspend/resume.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-pxa/generic.h b/arch/arm/mach-pxa/generic.h
index 041c048..dc876a8 100644
--- a/arch/arm/mach-pxa/generic.h
+++ b/arch/arm/mach-pxa/generic.h
@@ -65,4 +65,5 @@
 
 extern struct sysdev_class pxa_irq_sysclass;
 extern struct sysdev_class pxa_gpio_sysclass;
+extern struct sysdev_class pxa2xx_mfp_sysclass;
 extern struct sysdev_class pxa3xx_mfp_sysclass;