board: purism: add the Purism Librem5 phone

Initial commit of Librem5 u-boot and SPL

Signed-off-by: Angus Ainslie <angus@akkea.ca>
Co-developed-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Fabio Estevam <festevam@denx.de>
19 files changed