zephyr: select USE_DT_CODE_PARTITION after kconfig option change

Zephyr commit [1] has changed kconfig option name. Update kconfig
selection to the new one.

[1] 90b9eb3a9e93 ("kconfig: Rename USE_CODE_PARTITION to
  USE_DT_CODE_PARTITION")

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index 252093a..8402fc1 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -13,7 +13,7 @@
 	default y
 	bool
 	select MPU_ALLOW_FLASH_WRITE if ARM_MPU
-	select USE_CODE_PARTITION if HAS_FLASH_LOAD_OFFSET
+	select USE_DT_CODE_PARTITION if HAS_FLASH_LOAD_OFFSET
 
 config BOOT_USE_MBEDTLS
 	bool