log: Allow padding of the function name

At present when function names are logged, the output is a little hard to
read since every function is a different length. Add a way to pad the
names so that the log messages line up vertically. This doesn't work if
the function name is very long, but it makes a big difference in most
cases.

Use 20 characters as a default since this covers the vast majority of
functions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/Kconfig b/common/Kconfig
index 1f0c366..2ab20a6 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -322,6 +322,14 @@
 	  Show the function name in log messages by default. This value can
 	  be overridden using the 'log format' command.
 
+config LOGF_FUNC_PAD
+	int "Number of characters to use for function"
+	default 20
+	help
+	  Sets the field width to use when showing the function. Set this to
+	  a larger value if you have lots of long function names, and want
+	  things to line up.
+
 config LOG_SYSLOG
 	bool "Log output to syslog server"
 	depends on NET