ARM: LPC32xx: Fix irq on GPI_28

The GPI_28 IRQ was not registered properly. The registration of
IRQ_LPC32XX_GPI_28 was added and the (wrong) IRQ_LPC32XX_GPI_11 at
LPC32XX_SIC1_IRQ(4) was replaced by IRQ_LPC32XX_GPI_28 (see manual of
LPC32xx / interrupt controller).

Signed-off-by: Roland Stigge <stigge@antcom.de>
Cc: stable@vger.kernel.org