boot: zephyr: fix compilation with CONFIG_LOG_MINIMAL=y

Fix compilation with CONFIG_LOG_MINIMAL enabled by disabling the
custom log handling code.

Fixes e75e33d9817fefb8ec37b5979f93e3dd41e81b8f

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
diff --git a/boot/zephyr/main.c b/boot/zephyr/main.c
index 19c9995..e1697db 100644
--- a/boot/zephyr/main.c
+++ b/boot/zephyr/main.c
@@ -51,7 +51,8 @@
 #include <arm_cleanup.h>
 #endif
 
-#if defined(CONFIG_LOG) && !defined(CONFIG_LOG_IMMEDIATE)
+#if defined(CONFIG_LOG) && !defined(CONFIG_LOG_IMMEDIATE) && \
+    !defined(CONFIG_LOG_MINIMAL)
 #ifdef CONFIG_LOG_PROCESS_THREAD
 #warning "The log internal thread for log processing can't transfer the log"\
          "well for MCUBoot."
@@ -258,7 +259,7 @@
 #endif
 
 #if defined(CONFIG_LOG) && !defined(CONFIG_LOG_IMMEDIATE) &&\
-    !defined(CONFIG_LOG_PROCESS_THREAD)
+    !defined(CONFIG_LOG_PROCESS_THREAD) && !defined(CONFIG_LOG_MINIMAL)
 /* The log internal thread for log processing can't transfer log well as has too
  * low priority.
  * Dedicated thread for log processing below uses highest application