staging: r8188eu: Fix smatch warnings in os_dep/ioctl_linux.c

Smatch reports the following:
drivers/staging/rtl8188eu/os_dep/ioctl_linux.c:941 rtw_wx_set_pmkid() warn: add some parenthesis here?
drivers/staging/rtl8188eu/os_dep/ioctl_linux.c:1042 rtw_wx_get_range() warn: assigning (-78) to unsigned variable 'range->avg_qual.level'
drivers/staging/rtl8188eu/os_dep/ioctl_linux.c:2629 rtw_get_ap_info() warn: add some parenthesis here?
drivers/staging/rtl8188eu/os_dep/ioctl_linux.c:4043 rtw_rereg_nd_name() warn: add some parenthesis here?
drivers/staging/rtl8188eu/os_dep/ioctl_linux.c:4052 rtw_rereg_nd_name() warn: add some parenthesis here?

The warnings calling for adding parentheses all have "if (!memcmp() == true)" and
are fixed by removing the "==true" part.

The warning where a negative number is stored in an unsigned variable is fixed
by biasing the result by 256.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>