boot: zephyr: board: various: Remove size optimisation

This value is now the default, remove explicitly setting it for
some boards

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>
diff --git a/boot/zephyr/boards/circuitdojo_feather_nrf9160.conf b/boot/zephyr/boards/circuitdojo_feather_nrf9160.conf
index 656239c..c23f92c 100644
--- a/boot/zephyr/boards/circuitdojo_feather_nrf9160.conf
+++ b/boot/zephyr/boards/circuitdojo_feather_nrf9160.conf
@@ -11,6 +11,3 @@
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_DETECT_DELAY=450
 CONFIG_MCUBOOT_INDICATION_LED=y
-
-# Size of mcuboot partition
-CONFIG_SIZE_OPTIMIZATIONS=y
\ No newline at end of file
diff --git a/boot/zephyr/boards/conexio_stratus.conf b/boot/zephyr/boards/conexio_stratus.conf
index 5a29000..79ba798 100644
--- a/boot/zephyr/boards/conexio_stratus.conf
+++ b/boot/zephyr/boards/conexio_stratus.conf
@@ -13,6 +13,3 @@
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_DETECT_DELAY=450
 CONFIG_MCUBOOT_INDICATION_LED=y
-
-# Size of mcuboot partition
-CONFIG_SIZE_OPTIMIZATIONS=y
diff --git a/boot/zephyr/boards/nrf51dk_nrf51422.conf b/boot/zephyr/boards/nrf51dk_nrf51422.conf
index bd4eaac..b6d5ae5 100644
--- a/boot/zephyr/boards/nrf51dk_nrf51422.conf
+++ b/boot/zephyr/boards/nrf51dk_nrf51422.conf
@@ -3,4 +3,3 @@
 # partition size with a zephyr DTS overlay to make MCUboot's debug
 # builds fit.
 CONFIG_LOG=n
-CONFIG_SIZE_OPTIMIZATIONS=y
diff --git a/boot/zephyr/boards/nrf52_minimal_footprint.conf b/boot/zephyr/boards/nrf52_minimal_footprint.conf
index e070b2d..a290312 100644
--- a/boot/zephyr/boards/nrf52_minimal_footprint.conf
+++ b/boot/zephyr/boards/nrf52_minimal_footprint.conf
@@ -59,6 +59,3 @@
 
 # Console
 CONFIG_STDOUT_CONSOLE=n
-
-# Build
-CONFIG_SIZE_OPTIMIZATIONS=y
diff --git a/boot/zephyr/boards/sparkfun_thing_plus_nrf9160.conf b/boot/zephyr/boards/sparkfun_thing_plus_nrf9160.conf
index 656239c..c23f92c 100644
--- a/boot/zephyr/boards/sparkfun_thing_plus_nrf9160.conf
+++ b/boot/zephyr/boards/sparkfun_thing_plus_nrf9160.conf
@@ -11,6 +11,3 @@
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_DETECT_DELAY=450
 CONFIG_MCUBOOT_INDICATION_LED=y
-
-# Size of mcuboot partition
-CONFIG_SIZE_OPTIMIZATIONS=y
\ No newline at end of file