optee: Add optee_image_get_entry_point()

optee: Add optee_image_get_entry_point()

Add a helper function for extracting the least significant 32 bits from the
OPTEE entry point address, which will be good enough to load OPTEE binaries
up to (2^32)-1 bytes.

We may need to extend this out later on but for now (2^32)-1 should be
fine.

Signed-off-by: Bryan O'Donoghue <[email protected]>
Cc: Harinarayan Bhatta <[email protected]>
Cc: Andrew F. Davis <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Kever Yang <[email protected]>
Cc: Philipp Tomsich <[email protected]>
Cc: Peng Fan <[email protected]>
Tested-by: Peng Fan <[email protected]>