rtl8xxxu: Add mbox extension register definitions for 8723B

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_regs.h

@@ -341,6 +341,11 @@
 #define REG_BB_ACCEESS_CTRL		0x01e8
 #define REG_BB_ACCESS_DATA		0x01ec
 
+#define REG_HMBOX_EXT0_8723B		0x01f0
+#define REG_HMBOX_EXT1_8723B		0x01f4
+#define REG_HMBOX_EXT2_8723B		0x01f8
+#define REG_HMBOX_EXT3_8723B		0x01fc
+
 /* 0x0200 ~ 0x027F	TXDMA Configuration */
 #define REG_RQPN			0x0200
 #define  RQPN_HI_PQ_SHIFT		0