b43: Kconfig: let config B43_BCMA_PIO depends on B43

Logically, config B43_BCMA_PIO should depend on B43. This also solves
the problem that sub options of b43 driver didn't indent correctly in
make menuconfig's ncurses window.
Signed-off-by: NZhao, Gang <gamerh2o@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/Kconfig

@@ -92,7 +92,7 @@ config B43_SDIO
 # if we can do DMA.
 config B43_BCMA_PIO
 	bool
-	depends on B43_BCMA
+	depends on B43 && B43_BCMA
 	select BCMA_BLOCKIO
 	default y