broadcom_sta: fix build on linux-5.1

pkgs/os-specific/linux/broadcom-sta/default.nix

···
     # source: https://aur.archlinux.org/cgit/aur.git/tree/linux412.patch?h=broadcom-wl
     ./linux-4.12.patch
     ./linux-4.15.patch
+    ./linux-5.1.patch
     ./null-pointer-fix.patch
     ./gcc.patch
   ];

pkgs/os-specific/linux/broadcom-sta/linux-5.1.patch

···
+commit bcb06af629a36eb84f9a35ac599ec7e51e2d39fb
+Author: georgewhewell <[e-mail]>
+Date:   Sat May 18 21:22:37 2019 +0100
+
+    find src -type f -name \'*.c\' -exec sed -i "s/get_ds()/KERNEL_DS/g" {} \;
+
+diff --git a/src/wl/sys/wl_cfg80211_hybrid.c b/src/wl/sys/wl_cfg80211_hybrid.c
+index 7b606e0..51c81bc 100644
+--- a/src/wl/sys/wl_cfg80211_hybrid.c
++++ b/src/wl/sys/wl_cfg80211_hybrid.c
+@@ -450,7 +450,7 @@ wl_dev_ioctl(struct net_device *dev, u32 cmd, void *arg, u32 len)
+ 	ifr.ifr_data = (caddr_t)&ioc;
+ 
+ 	fs = get_fs();
+-	set_fs(get_ds());
++	set_fs(KERNEL_DS);
+ #if defined(WL_USE_NETDEV_OPS)
+ 	err = dev->netdev_ops->ndo_do_ioctl(dev, &ifr, SIOCDEVPRIVATE);
+ #else
+diff --git a/src/wl/sys/wl_iw.c b/src/wl/sys/wl_iw.c
+index c4c610b..9c3c74e 100644
+--- a/src/wl/sys/wl_iw.c
++++ b/src/wl/sys/wl_iw.c
+@@ -117,7 +117,7 @@ dev_wlc_ioctl(
+ 	ifr.ifr_data = (caddr_t) &ioc;
+ 
+ 	fs = get_fs();
+-	set_fs(get_ds());
++	set_fs(KERNEL_DS);
+ #if defined(WL_USE_NETDEV_OPS)
+ 	ret = dev->netdev_ops->ndo_do_ioctl(dev, &ifr, SIOCDEVPRIVATE);
+ #else