staging: rtl8723bs: use DIV_ROUND_UP helper macro

Use the DIV_ROUND_UP macro to replace open-coded divisor calculation
to improve readability.
Issue found using coccinelle:
@@
expression n,d;
@@
(
- ((n + d - 1) / d)
+ DIV_ROUND_UP(n,d)
|
- ((n + (d - 1)) / d)
+ DIV_ROUND_UP(n,d)
)
Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Link: https://lore.kernel.org/r/20191013191027.6470-1-wambui.karugax@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c

@@ -4156,9 +4156,8 @@ void SetHwReg8723B(struct adapter *padapter, u8 variable, u8 *val)
 				break;
 			}
 
-			/*  The value of ((usNavUpper + HAL_NAV_UPPER_UNIT_8723B - 1) / HAL_NAV_UPPER_UNIT_8723B) */
-			/*  is getting the upper integer. */
-			usNavUpper = (usNavUpper + HAL_NAV_UPPER_UNIT_8723B - 1) / HAL_NAV_UPPER_UNIT_8723B;
+			usNavUpper = DIV_ROUND_UP(usNavUpper,
+						  HAL_NAV_UPPER_UNIT_8723B);
 			rtw_write8(padapter, REG_NAV_UPPER, (u8)usNavUpper);
 		}
 		break;