staging: rtl8723bs: os_dep: Remove space after cast

Remove space after cast to fix checkpatch issue.
CHECK: No space is necessary after a cast

Signed-off-by: Mamta Shukla <mamtashukla555@gmail.com>
ACKed-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>