lib: optee: remove the duplicate CONFIG_OPTEE

The configuration CONFIG_OPTEE is defined 2 times:
1- in lib/optee/Kconfig for support of OPTEE images loaded by bootm command
2- in drivers/tee/optee/Kconfig for support of OP-TEE driver.

It is abnormal to have the same CONFIG define for 2 purpose;
and it is difficult to managed correctly their dependencies.

Moreover CONFIG_SPL_OPTEE is defined in common/spl/Kconfig
to manage OPTEE image load in SPL.

This definition causes an issue with the macro CONFIG_IS_ENABLED(OPTEE)
to test the availability of the OP-TEE driver.

This patch cleans the configuration dependency with:
- CONFIG_OPTEE_IMAGE (renamed) => support of OP-TEE image in U-Boot
- CONFIG_SPL_OPTEE_IMAGE (renamed) => support of OP-TEE image in SPL
- CONFIG_OPTEE (same) => support of OP-TEE driver in U-Boot
- CONFIG_OPTEE_LIB (new) => support of OP-TEE library

After this patch, the macro have the correct behavior:
- CONFIG_IS_ENABLED(OPTEE_IMAGE) => Load of OP-TEE image is supported
- CONFIG_IS_ENABLED(OPTEE) => OP-TEE driver is supported

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/configs/evb-rk3288_defconfig b/configs/evb-rk3288_defconfig
index efb2a3e..eca9f5c 100644
--- a/configs/evb-rk3288_defconfig
+++ b/configs/evb-rk3288_defconfig
@@ -25,7 +25,7 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN=0x10000
-CONFIG_SPL_OPTEE=y
+CONFIG_SPL_OPTEE_IMAGE=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_GPT=y
 CONFIG_CMD_I2C=y