Staging: bcm: Change the style of comparing structures to null in InterfaceMisc.c.

This patch changes the style of comparing
structures to null. Instead of this:
"if (foo == NULL) {" or "if (foo != NULL) {",
the new logic uses: "if (!foo) {" or
"if (foo) {".

Signed-off-by: Kevin McKinney <klmckinney1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>