staging: r8188eu: use max() and min() macros

staging: r8188eu: use max() and min() macros

use max() and min() macros to fix following cocci warnings:

	drivers/staging/r8188eu/core/rtw_wlan_util.c:719: WARNING opportunity for min()
	drivers/staging/r8188eu/core/rtw_wlan_util.c:724: WARNING opportunity for max()

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vihas Mak <makvihas@gmail.com>
Link: https://lore.kernel.org/r/20211124190436.251312-1-makvihas@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>