usb: renesas_usbhs: replace udelay() with usleep_range()

According to Documentation/timers/timers-howto.txt, a driver should
use usleep_range() instead of udelay() on NON-ATOMIC CONTEXT if
"SLEEPING FOR ~USECS OR SMALL MSECS ( 10us - 20ms)".

Since the .hardware_init() and .power_ctrl() will run on NON-ATOMIC
CONTEXT, this patch replaces udelay() with usleep_range().

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>