Code cleanup after changes for Bug 56628.  The general approach for 
InnoDB is to make a reference to each enum value whenever it is used in a
switch statement.  In addition, no default case should be used for switch 
statements on enum types.  This assures that if there is ever any change 
in the enum values, the switch will need to change to reflect it since a 
compiler warning will occur.  In this case, the enum row_type is declared 
in handler.h and could be changed for another storage engine.  If so, a 
warning will occur in the InnoDB build.  

Other changes;
* This patch uses 2 macros to help consolidate warning messages that
   need to occur twice in the single switch for row_format.
* Using row_format as the variable name to distinguish it from the enum
  type.
* Function declaration format correction.