cli: allow users to determine history buffer allocation method

This commit allows users to choose the appropriate memory
allocation method between static allocated and dynamically
calloc. The previous static-array way will not obviously
contribute to the final binary size since it is uninitialized,
and might have better performance than the dynamical one.
Now we provide the users with both the two options.

Signed-off-by: Hanyuan Zhao <hanyuan-z@qq.com>

cmd/Kconfig

@@ -189,6 +189,17 @@ config CMD_HISTORY
 	  Show the command-line history, i.e. a list of commands that are in
 	  the history buffer.
 
+config CMD_HISTORY_USE_CALLOC
+	bool "dynamically allocate memory"
+	default y
+	depends on CMD_HISTORY
+	help
+	  Saying Y to this will use calloc to get the space for history
+	  storing. Otherwise the history buffer will be an uninitialized
+	  static array directly, without the memory allocation, and it is
+	  writable after relocation to RAM. If u-boot is running from ROM
+	  all the time or unsure, say Y to this.
+
 config CMD_LICENSE
 	bool "license"
 	select BUILD_BIN2C