ide-dma: don't reset request fields on dma_timeout_retry()

Impact: drop unnecessary code

Now that everything uses bio and block operations, there is no need to
reset request fields manually when retrying a request.  Every field is
guaranteed to be always valid.  Drop unnecessary request field
resetting from ide_dma_timeout_retry().

Signed-off-by: Tejun Heo <tj@kernel.org>