Staging: rtl8192u: Remove useless comments

Remove the commented out places where macros PlatformAcquireSpinLock and
PlatformReleaseSpinLock are called as these macros are no longer used.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>