IDE: fix bug in reset sequence

According to the ata (ata5) specification the RESET- signal
shall be asserted for at least 25 us. Without this patch,
the RESET- signal is asserted on some boards for only < 1 us
(e. g. on the TQM5200). This patch adds a general delay of
25 us to the RESET- signal.

Without this patch a Platinum 4 GiB CF card is not recognised
properly on boards with a TQM5200 (STK52xx, TB5200).

Signed-off-by: Martin Krause <martin.krause@tqs.de>