Ignore the emulated wiimotes speaker data if the sample rate is set at 0hz.

Fixes issue 7806.
Packed the emu wiimote structs, removed swap16 and removed the speaker amp as the amp was distorting the audio.
DolphinWX: Remove unnecessary forward declarations
Merge pull request #1516 from lioncash/fwd

DolphinWX: Remove unnecessary forward declarations
Merge pull request #1508 from skidau/emu-wiimote-speaker-sample-rate-zero

Ignore the emulated wiimotes speaker data if the sample rate is set at 0hz