[ARM] pxa: enable GPIO receivers after configuring pins

'mach-pxa' platforms currently rely on a bootloader to setup GPIO pins
and clear RDH (to enable inputs).

A kernel loaded by a 'minimal' bootloader, that doesn't touch any pins,
will not function correctly; inputs will remain disabled, even after the
pins are configured. The following change fixes the issue and has been
verified on Gumstix Verdex XL6P and a custom PXA270 platform.
Signed-off-by: Timothy Clacy <tcl@phaseone.com>
Signed-off-by: Eric Miao <eric.miao@marvell.com>

arch/arm/mach-pxa/mfp-pxa2xx.c

@@ -377,6 +377,9 @@ static int __init pxa2xx_mfp_init(void)
 	if (cpu_is_pxa27x())
 		pxa27x_mfp_init();
 
+	/* clear RDH bit to enable GPIO receivers after reset/sleep exit */
+	PSSR = PSSR_RDH;
+
 	/* initialize gafr_run[], pgsr_lpm[] from existing values */
 	for (i = 0; i <= gpio_to_bank(pxa_last_gpio); i++)
 		gpdr_lpm[i] = GPDR(i * 32);