imx: use generic name ele(EdgeLockSecure Enclave)

Per NXP requirement, we rename all the NXP EdgeLock Secure Enclave
code including comment, folder and API name to ELE to align.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4604d41..17d69d2 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -882,7 +882,7 @@
 	select SUPPORT_SPL
 	select GPIO_EXTRA_HEADER
 	select MISC
-	select IMX_SENTINEL
+	select IMX_ELE
 	imply CMD_DM
 
 config ARCH_IMX9
@@ -894,7 +894,7 @@
 	select SUPPORT_SPL
 	select GPIO_EXTRA_HEADER
 	select MISC
-	select IMX_SENTINEL
+	select IMX_ELE
 	imply CMD_DM
 
 config ARCH_IMXRT