ctl: fix wrong operation for values in enumerated type of element

ctl: fix wrong operation for values in enumerated type of element

The 'snd_ctl_elem_value' structure includes union member for values.
Although it includes 'enumerated' member for values in enumerated type
of element, current implementation of alsactl library uses 'integer'
member to pick up the values. As a result, in any 64 bit System V ABI,
the library fails to get/set values for the enumerated type of
element. This commit fixes the bug.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>