staging: rtl8192u: fixed coding style issues in r8192U_core.c

This patch fixes some coding style issuses in r8192U_core.c
No logic is changed

Signed-off-by: Patrik Kårlin <patrik.karlin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>