wireless: cw1200: acquire hwbus lock around cw1200_irq_handler() call.

This fixes "lost interrupt" problems that occurred on SPI-based systems.
cw1200_irq_handler() expects the hwbus to be locked, but on the
SPI-path, that lock wasn't taken (unlike in the SDIO-path, where the
generic SDIO-code takes care of acquiring the lock).

Cc: stable@vger.kernel.org
Signed-off-by: David Mosberger <davidm@egauge.net>
Signed-off-by: Solomon Peachy <pizza@shaftnet.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/cw1200/cw1200_spi.c

@@ -237,7 +237,9 @@ static irqreturn_t cw1200_spi_irq_handler(int irq, void *dev_id)
 	struct hwbus_priv *self = dev_id;
 
 	if (self->core) {
+		cw1200_spi_lock(self);
 		cw1200_irq_handler(self->core);
+		cw1200_spi_unlock(self);
 		return IRQ_HANDLED;
 	} else {
 		return IRQ_NONE;