The BSEC OTP holds information about SoC type and package.
The Tamp registers hold information from the BootROM about boot
source. Add support for both.

Additionally, the tamp registers can also hold a request from the
operating system about what mode to enter after boot, e.g.
boot-into-recovery. A global function is exported for this, but
unused so far.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>