staging: rts5208: fix static checker warnings

The patch fa590c22: "staging: rts5208: add support for rts5208
and rts5288" from Nov 12, 2013, leads to the following static checker
warning:
	drivers/staging/rts5208/rtsx_chip.c:107 rtsx_enable_bus_int()
	warn: add curly braces?
This warning is produced because incorrect code indent.
Signed-off-by: Micky Ching <micky_ching@realsil.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>