b43: Remove unnecessary MMIO in interrupt hotpath

This removes unnecessary MMIO accesses in the interrupt hotpath.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43/b43.h b/drivers/net/wireless/b43/b43.h
index cc1db7e..4e8ad84 100644
--- a/drivers/net/wireless/b43/b43.h
+++ b/drivers/net/wireless/b43/b43.h
@@ -778,8 +778,8 @@
 	/* Reason code of the last interrupt. */
 	u32 irq_reason;
 	u32 dma_reason[6];
-	/* saved irq enable/disable state bitfield. */
-	u32 irq_savedstate;
+	/* The currently active generic-interrupt mask. */
+	u32 irq_mask;
 	/* Link Quality calculation context. */
 	struct b43_noise_calculation noisecalc;
 	/* if > 0 MAC is suspended. if == 0 MAC is enabled. */