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 <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>

include/tee/optee.h

@@ -29,6 +29,13 @@ struct optee_header {
 	uint32_t paged_size;
 };
 
+static inline uint32_t optee_image_get_entry_point(const image_header_t *hdr)
+{
+	struct optee_header *optee_hdr = (struct optee_header *)(hdr + 1);
+
+	return optee_hdr->init_load_addr_lo;
+}
+
 #if defined(CONFIG_OPTEE)
 int optee_verify_image(struct optee_header *hdr, unsigned long tzdram_start,
 		       unsigned long tzdram_len, unsigned long image_len);