b43: avoid uninitialized variable warnings in phy_n

  CC [M]  drivers/net/wireless/b43/phy_n.o
drivers/net/wireless/b43/phy_n.c: In function ‘b43_nphy_set_channel’:
drivers/net/wireless/b43/phy_n.c:3848:47: warning: ‘tabent_r2’ may be used uninitialized in this function
drivers/net/wireless/b43/phy_n.c:3849:47: warning: ‘tabent_r3’ may be used uninitialized in this function
drivers/net/wireless/b43/phy_n.c: In function ‘b43_nphy_poll_rssi.clone.14’:
drivers/net/wireless/b43/phy_n.c:2270:6: warning: ‘save_regs_phy$7’ may be used uninitialized in this function
drivers/net/wireless/b43/phy_n.c:2270:6: warning: ‘save_regs_phy$8’ may be used uninitialized in this function

FWIW, the usage of these variables is goverened by checks that match
their initializations.  So, I think these are actually false warnings.
Still, I would rather avoid the warning SPAM...
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/phy_n.c

@@ -2281,6 +2281,7 @@ static int b43_nphy_poll_rssi(struct b43_wldev *dev, u8 type, s32 *buf,
 		save_regs_phy[5] = b43_phy_read(dev, B43_NPHY_AFECTL_OVER);
 		save_regs_phy[6] = b43_phy_read(dev, B43_NPHY_TXF_40CO_B1S0);
 		save_regs_phy[7] = b43_phy_read(dev, B43_NPHY_TXF_40CO_B32S1);
+		save_regs_phy[8] = 0;
 	} else {
 		save_regs_phy[0] = b43_phy_read(dev, B43_NPHY_AFECTL_C1);
 		save_regs_phy[1] = b43_phy_read(dev, B43_NPHY_AFECTL_C2);
@@ -2289,6 +2290,8 @@ static int b43_nphy_poll_rssi(struct b43_wldev *dev, u8 type, s32 *buf,
 		save_regs_phy[4] = b43_phy_read(dev, B43_NPHY_RFCTL_OVER);
 		save_regs_phy[5] = b43_phy_read(dev, B43_NPHY_RFCTL_RSSIO1);
 		save_regs_phy[6] = b43_phy_read(dev, B43_NPHY_RFCTL_RSSIO2);
+		save_regs_phy[7] = 0;
+		save_regs_phy[8] = 0;
 	}
 
 	b43_nphy_rssi_select(dev, 5, type);
@@ -3845,8 +3848,8 @@ static int b43_nphy_set_channel(struct b43_wldev *dev,
 {
 	struct b43_phy *phy = &dev->phy;
 
-	const struct b43_nphy_channeltab_entry_rev2 *tabent_r2;
-	const struct b43_nphy_channeltab_entry_rev3 *tabent_r3;
+	const struct b43_nphy_channeltab_entry_rev2 *tabent_r2 = NULL;
+	const struct b43_nphy_channeltab_entry_rev3 *tabent_r3 = NULL;
 
 	u8 tmp;