boards: arm: lpc55s: Add missing trustzone flag

This commit adds the missing `ARM_TRUSTZONE_M` config flag
from TrustZone-enabled cores on LPC55sxx board targets.

Signed-off-by: Kevin Townsend <kevin.townsend@linaro.org>
diff --git a/boards/arm/lpcxpresso55s16/lpcxpresso55s16_ns_defconfig b/boards/arm/lpcxpresso55s16/lpcxpresso55s16_ns_defconfig
index 255c9bd..6890349 100644
--- a/boards/arm/lpcxpresso55s16/lpcxpresso55s16_ns_defconfig
+++ b/boards/arm/lpcxpresso55s16/lpcxpresso55s16_ns_defconfig
@@ -19,5 +19,6 @@
 
 # TrustZone-M non-secure
 CONFIG_TRUSTED_EXECUTION_NONSECURE=y
+CONFIG_ARM_TRUSTZONE_M=y
 
 CONFIG_RUNTIME_NMI=y
diff --git a/boards/arm/lpcxpresso55s28/lpcxpresso55s28_defconfig b/boards/arm/lpcxpresso55s28/lpcxpresso55s28_defconfig
index ad316aa..04f5249 100644
--- a/boards/arm/lpcxpresso55s28/lpcxpresso55s28_defconfig
+++ b/boards/arm/lpcxpresso55s28/lpcxpresso55s28_defconfig
@@ -20,6 +20,7 @@
 
 # Enable TrustZone-M
 CONFIG_TRUSTED_EXECUTION_SECURE=y
+CONFIG_ARM_TRUSTZONE_M=y
 
 CONFIG_RUNTIME_NMI=y
 
diff --git a/boards/arm/lpcxpresso55s28/lpcxpresso55s28_ns_defconfig b/boards/arm/lpcxpresso55s28/lpcxpresso55s28_ns_defconfig
index e7cc6c5..44fde1a 100644
--- a/boards/arm/lpcxpresso55s28/lpcxpresso55s28_ns_defconfig
+++ b/boards/arm/lpcxpresso55s28/lpcxpresso55s28_ns_defconfig
@@ -22,6 +22,7 @@
 # Enable TrustZone-M
 CONFIG_TRUSTED_EXECUTION_NONSECURE=y
 CONFIG_RUNTIME_NMI=y
+CONFIG_ARM_TRUSTZONE_M=y
 # TFM will run without MCUboot
 CONFIG_TFM_BL2=n
 
diff --git a/boards/arm/lpcxpresso55s69/lpcxpresso55s69_cpu0_defconfig b/boards/arm/lpcxpresso55s69/lpcxpresso55s69_cpu0_defconfig
index 85c43ed..4ff747b 100644
--- a/boards/arm/lpcxpresso55s69/lpcxpresso55s69_cpu0_defconfig
+++ b/boards/arm/lpcxpresso55s69/lpcxpresso55s69_cpu0_defconfig
@@ -20,5 +20,6 @@
 
 # Enable TrustZone-M
 CONFIG_TRUSTED_EXECUTION_SECURE=y
+CONFIG_ARM_TRUSTZONE_M=y
 
 CONFIG_RUNTIME_NMI=y
diff --git a/boards/arm/lpcxpresso55s69/lpcxpresso55s69_ns_defconfig b/boards/arm/lpcxpresso55s69/lpcxpresso55s69_ns_defconfig
index b8e8139..08612f5 100644
--- a/boards/arm/lpcxpresso55s69/lpcxpresso55s69_ns_defconfig
+++ b/boards/arm/lpcxpresso55s69/lpcxpresso55s69_ns_defconfig
@@ -22,5 +22,6 @@
 # Enable TrustZone-M
 CONFIG_TRUSTED_EXECUTION_NONSECURE=y
 CONFIG_RUNTIME_NMI=y
+CONFIG_ARM_TRUSTZONE_M=y
 
 CONFIG_BUILD_OUTPUT_HEX=y