boot: zephyr: migrate to new log subystem

The old log subsystem has been deprecated in Zephyr.
Migrate to the new subsystem to avoid compilation warnings.

In-place log processing is selected as it is required as MCUBoot is
one thread application.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>
Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index e87db5a..2ce1b2d 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -132,10 +132,11 @@
 config BOOT_HAVE_LOGGING
 	bool "MCUboot have logging enabled"
 	default y
-	select SYS_LOG
+	select LOG
+	select LOG_INPLACE_PROCESS
 	help
 	  If y, enables logging on the serial port. The log level can
-	  be defined by setting `SYS_LOG_DEFAULT_LEVEL`.
+	  be defined by setting `LOG_DEFAULT_LEVEL`.
 	  If unsure, leave at the default value.
 
 menuconfig MCUBOOT_SERIAL