kernel: Move modifications of b53.h into patch

The b53 driver was added as a dsa driver into the mainline Linux kernel,
but we still use the swconfig based driver. The header file b53.h is
used by both drivers, but the swconfig one needs an extra member, add
this one in a patch to not overwrite the version shipped with the
mainline kernel.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/generic/hack-4.9/700-swconfig_switch_drivers.patch

@@ -136,3 +136,15 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  header-y += synclink.h
  header-y += sync_file.h
  header-y += sysctl.h
+--- a/include/linux/platform_data/b53.h
++++ b/include/linux/platform_data/b53.h
+@@ -25,6 +25,9 @@ struct b53_platform_data {
+ 	u32 chip_id;
+ 	u16 enabled_ports;
+ 
++	/* allow to specify an ethX alias */
++	const char *alias;
++
+ 	/* only used by MMAP'd driver */
+ 	unsigned big_endian:1;
+ 	void __iomem *regs;