b43: Replace mdelay with usleep_range in b43_radio_2057_init_post

b43_radio_2057_init_post is not called in an interrupt handler
nor holding a spinlock.
The function mdelay in it can be replaced with usleep_range,
to reduce busy wait.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/b43/phy_n.c

@@ -1031,7 +1031,7 @@ static void b43_radio_2057_init_post(struct b43_wldev *dev)
 
 	b43_radio_set(dev, R2057_RFPLL_MISC_CAL_RESETN, 0x78);
 	b43_radio_set(dev, R2057_XTAL_CONFIG2, 0x80);
-	mdelay(2);
+	usleep_range(2000, 3000);
 	b43_radio_mask(dev, R2057_RFPLL_MISC_CAL_RESETN, ~0x78);
 	b43_radio_mask(dev, R2057_XTAL_CONFIG2, ~0x80);