optee: Add CONFIG_OPTEE_TZDRAM_SIZE

optee: Add CONFIG_OPTEE_TZDRAM_SIZE

OPTEE is currently linked to a specific area of memory called the TrustZone
DRAM. This patch adds a CONFIG entry for the default size of TrustZone DRAM
that a board-port can over-ride. The region that U-Boot sets aside for the
OPTEE run-time should be verified before attempting to hand off to the
OPTEE run-time. Each board-port should carefully ensure that the TZDRAM
size specified in the OPTEE build and the TZDRAM size specified in U-Boot
match-up.

Further patches will use TZDRAM size with other defines and variables to
carry out a degree of automated verification in U-Boot prior to trying to
boot an OPTEE image.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Harinarayan Bhatta <harinarayan@ti.com>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Kever Yang <kever.yang@rock-chips.com>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Cc: Peng Fan <peng.fan@nxp.com>
Tested-by: Peng Fan <peng.fan@nxp.com>