staging: rtl8723bs: remove set but not used variable 'change', 'pos'

staging: rtl8723bs: remove set but not used variable 'change', 'pos'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c: In function cfg80211_rtw_change_iface:
drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:1310:5: warning: variable change set but not used [-Wunused-but-set-variable]
drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c: In function rtw_cfg80211_set_wpa_ie:
drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:1803:19: warning: variable pos set but not used [-Wunused-but-set-variable]

They are introduced by commit 554c0a3abf21 ("staging:
Add rtl8723bs sdio wifi driver"), but never used, so remove them.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Link: https://lore.kernel.org/r/1574063156-68155-6-git-send-email-zhengbin13@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>