PCI: rcar: Poll more often in rcar_pcie_wait_for_dl()

PCI: rcar: Poll more often in rcar_pcie_wait_for_dl()

The data link active signal usually takes ~20 uSec to be asserted, poll
the bit more often to avoid useless delays in this function.

Use udelay() instead of usleep() for such a small delay as suggested by
the timer documentation.

Signed-off-by: Marek Vasut <[email protected]>
[[email protected]: updated commit log]
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Phil Edworthy <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Wolfram Sang <[email protected]>
Cc: [email protected]