rtl_bt: Add rtl8761bu firmware

From Realtek 20200806_LINUX_BT_DRIVER_RTL8761B_COEX_v0202
driver package.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

WHENCE

@@ -3762,6 +3762,8 @@ Link: rtl_bt/rtl8723bs_config-OBDA0623.bin -> rtl8723bs_config-OBDA8723.bin
 File: rtl_bt/rtl8761a_fw.bin
 File: rtl_bt/rtl8761b_fw.bin
 File: rtl_bt/rtl8761b_config.bin
+File: rtl_bt/rtl8761bu_fw.bin
+File: rtl_bt/rtl8761bu_config.bin
 File: rtl_bt/rtl8812ae_fw.bin
 File: rtl_bt/rtl8821a_fw.bin
 Link: rtl_bt/rtl8821a_config.bin -> rtl8821c_config.bin
@@ -3794,6 +3796,8 @@ File rtl_bt/rtl8822cu_config.bin came directly from Realtek.
 Found in vendor driver, 20200806_LINUX_BT_DRIVER_RTL8761B_COEX_v0202.zip
 File rtl_bt/rtl8761b_fw.bin
 File rtl_bt/rtl8761b_config.bin
+File rtl_bt/rtl8761bu_fw.bin
+File rtl_bt/rtl8761bu_config.bin
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 Driver: btmtk_usb - Bluetooth USB driver