This patch converts audio driver to use platform driver (and minor
style changes).

This fixes broken standby resume as reported in

http://linux.omap.com/pipermail/davinci-linux-open-source/2008-January/004919.html

Switching to platform_driver, the driver suspends and resumes properly
now. platform_resume_early() doesn't call uninitialized tasklet worker
function audio_dsr_handler() any more. From oops reported in link
above:

(audio_dsr_handler+0x0/0x7c) from [<c014f848>]
(platform_resume_early+0x30)
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Kevin Hilman <khilman@mvista.com>