can: sja1000: Replace mdelay with usleep_range in pcan_add_channels

pcan_add_channels() is never called in atomic context.

pcan_add_channels() is only called by pcan_probe(), which is only set as
".probe" in struct pcmcia_driver.

Despite never getting called from atomic context, pcan_add_channels()
calls mdelay() to busily wait.
This is not necessary and can be replaced with usleep_range() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/sja1000/peak_pcmcia.c

@@ -530,7 +530,7 @@ static int pcan_add_channels(struct pcan_pccard *card)
 	pcan_write_reg(card, PCC_CCR, ccr);
 
 	/* wait 2ms before unresetting channels */
-	mdelay(2);
+	usleep_range(2000, 3000);
 
 	ccr &= ~PCC_CCR_RST_ALL;
 	pcan_write_reg(card, PCC_CCR, ccr);