ide: pdc202xx_new PLL input clock fix

Recently the PLL input clock of Promise 2027x is sometimes detected
higher than expected (e.g. 20.027 MHz compared to 16.714 MHz).
It seems sometimes the mdelay() function is not as precise as it
used to be. Per Alan's advice, HT or power management might affect
the precision of mdelay().

This patch calls gettimeofday() to measure the time elapsed and
calculate the PLL input clock accordingly.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Bahadir Balban <bahadir.balban@gmail.com>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>