board: [cosmetic] tqma6: adjust SPDX tag

board: [cosmetic] tqma6: adjust SPDX tag

While at it, adjust the TQ-Systems copyright info to include
consistent company information, the mail address to reach all
developers at TQ-Systems for questions regarding U-Boot support
for our SOM and remove author's company mail address not suitable
for plain text mail.

Signed-off-by: Markus Niebel <Markus.Niebel@ew.tq-group.com>
Signed-off-by: Max Merchel <Max.Merchel@ew.tq-group.com>