pinctrl: sirf: add lost chained_irq_enter and exit in sirfsoc_gpio_handle_irq

This patch fixes the chained irq hang issue, tested by DM9000 driver using
GPIO0-3(irqnr=131) as the external IRQ on SiRFmarco:
   $ cat /proc/interrupts
               CPU0       CPU1
     32:       1608          0       GIC  sirfsoc_timer0
     33:          0       3197       GIC  sirfsoc_timer1
     50:      10207          0       GIC  sirfsoc-uart
     56:          2          0       GIC  cc0e0000.i2c
     70:         44          0       GIC  mmc0
    131:        333          0  sirf-gpio-irq  eth0
    ...

Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>