msm: board-9625: Remove nr_irqs assignment

Remove the machine configuration which sets nr_irqs = -1.  This
setting must be removed because it leads to an infinite loop in
init_irq_proc() when CONFIG_SPARSE_IRQ is enabled.

Change-Id: Id8a222d3060aa254600256b5e561edd4a849c816
Signed-off-by: David Collins <collinsd@codeaurora.org>