drivers: add missing SPDX-License-Identifier

This adds the suitable SPDX-License-Identifier to all files in drivers/
that previously lacked one.

To aid manual inspection, following heuristics can be used:

* No changes outside of comments/whitespace:

  git show -U0 HEAD | rg -v '^(@@|diff|index)|[-+]([-+]|//|#|[\s/]\*)'

* -or-later come in pairs:

  git show --inter-hunk-context=19 HEAD | \
    perl -0777 -F'/^@/gm' -ne 'for (@F) { @m = /later/g; print if @m & 1 }'

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20211030175632.2276077-4-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

0 files changed, 0 insertions, 0 deletions