menu.c: use puts() instead of printf() where possible

common/menu.c used printf() in a number of places to print user
provided, constant strings (like the "title" string).  printf() is
dangerous here for example in case the user unwittingly embeds some
'%' caracters that printf() would interpret as formatting and then
pick up random arguments.  Use puts() instead.

We also omit the trailing ':' in the title line - if a user wants
this, he can provide it as part of the title string.

Signed-off-by: Wolfgang Denk <wd@denx.de>