net: dsa: use capital "OR" for multiple licenses in SPDX

Documentation/process/license-rules.rst and checkpatch expect the SPDX
identifier syntax for multiple licenses to use capital "OR". Correct it
to keep consistent format and avoid copy-paste issues.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Kurt Kanzenbach <[e-mail]>
Reviewed-by: FLorian Fainelli <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/b53/b53_serdes.c

···
-// SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 /*
  * Northstar Plus switch SerDes/SGMII PHY main logic
  *

drivers/net/dsa/b53/b53_serdes.h

···
-/* SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause */
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
 /*
  * Northstar Plus switch SerDes/SGMII PHY definitions
  *

drivers/net/dsa/hirschmann/hellcreek.c

···
-// SPDX-License-Identifier: (GPL-2.0 or MIT)
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
 /*
  * DSA driver for:
  * Hirschmann Hellcreek TSN switch.

drivers/net/dsa/hirschmann/hellcreek.h

···
-/* SPDX-License-Identifier: (GPL-2.0 or MIT) */
+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
 /*
  * DSA driver for:
  * Hirschmann Hellcreek TSN switch.

include/linux/platform_data/hirschmann-hellcreek.h

···
-/* SPDX-License-Identifier: (GPL-2.0 or MIT) */
+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
 /*
  * Hirschmann Hellcreek TSN switch platform data.
  *