staging: greybus: add SPDX identifiers to all greybus driver files

staging: greybus: add SPDX identifiers to all greybus driver files

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the drivers/staging/greybus files files with the correct SPDX
license identifier based on the license text in the file itself.  The
SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Vaibhav Hiremath <[email protected]>
Cc: "Bryan O'Donoghue" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Acked-by: Vaibhav Agarwal <[email protected]>
Acked-by: David Lin <[email protected]>
Reviewed-by: Alex Elder <[email protected]>
Acked-by: Johan Hovold <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Acked-by: Mark Greer <[email protected]>
Acked-by: Rui Miguel Silva <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>