staging: rtl8192u: Removed redundant bool comparisons in r8192U_dm.c

This patch was detected with the help of coccinelle tool.
The redundant comparisons of bool variables are removed in r8192U_dm.c.

Signed-off-by: Harisangam Sharvari <sharisan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>