stream/syslog: use internal buffer to decoupling syslog with iob

Signed-off-by: chao an <anchao@xiaomi.com>

drivers/syslog/Kconfig

@@ -72,7 +72,6 @@ endif
 config SYSLOG_BUFFER
 	bool "Use buffered output"
 	default n
-	select MM_IOB
 	---help---
 		Enables an buffering logic that will be used to serialize debug
 		output from concurrent tasks. This enables allocation of one buffer
@@ -82,6 +81,16 @@ config SYSLOG_BUFFER
 		then the output from multiple tasks that attempt to generate SYSLOG
 		output may be interleaved and difficult to read.
 
+if SYSLOG_BUFFER
+
+config SYSLOG_BUFSIZE
+	int "Syslog buffer size"
+	default 64
+	---help---
+		The size of the syslog buffer in bytes.
+
+endif
+
 config SYSLOG_INTBUFFER
 	bool "Use interrupt buffer"
 	default n