b43: move under broadcom vendor directory

Part of reorganising wireless drivers directory and Kconfig.

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
diff --git a/drivers/net/wireless/broadcom/Makefile b/drivers/net/wireless/broadcom/Makefile
new file mode 100644
index 0000000..0140a81
--- /dev/null
+++ b/drivers/net/wireless/broadcom/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_B43)		+= b43/