xkb: Add missing LedClass and BellClass enum values

xkb: Add missing LedClass and BellClass enum values

The protocol encoding says:
http://www.x.org/releases/current/doc/kbproto/xkbproto.html#appD::Common_Types

    KB_LEDCLASSRESULT
        0     KbdFeedbackClass
        4     LedFeedbackClass

    KB_LEDCLASSSPEC
        Encoding same as KB_LEDCLASSRESULT, with the addition of:
        #x0300     XkbDfltXIClass
        #x0500     XkbAllXIClasses

    KB_BELLCLASSRESULT
        0     KbdFeedbackClass
        5     BellFeedbackClass

    KB_BELLCLASSSPEC
        Encoding same as KB_BELLCLASSRESULT, with the addition of:
        #x0300     XkbDfltXIClass

Note that the spec says something slightly different in another section:
http://www.x.org/releases/current/doc/kbproto/xkbproto.html#Common_Types

    KB_LEDCLASSSPEC { KbdFeedbackClass , LedFeedbackClass , DfltXIClass , AllXIClasses , XINone }
    KB_BELLCLASSSPEC    { KbdFeedbackClass , BellFeedbackClass , DfltXIClass , AllXIClasses  }}

From what I could gather, the encoding is the correct one (but I'm not
sure).

Signed-off-by: Ran Benita <ran234@gmail.com>
Reviewed-by: Daniel Martin <consume.noise@gmail.com>