res_config_mysql: Fix broken column type checking

MySQL configuration engine contains a bug in require_mysql(). This
function is used for column type checking in tables. This bug only
affects DATETIME, DATE and FLOAT types.

It came from mixing the first condition (switch-case-like
if/then/else), to check the expected column type, with the second
condition, to check the actual column type against the expected column
type. Both conditions must be checked separately in order to avoid the
execution of the wrong block.

ASTERISK-18252 #comment This patch might fix the issue
Reported by: Gareth Blades

ASTERISK-25041 #close
Reported by: Alexandre Fournier
Tested by: Alexandre Fournier

Change-Id: I0b8bf7e68ab938be8e6525a249260cb648cb0bfa