staging: xillybus: Fix if-else coding style errors

According to Documentation/CodingStyle, when one branch of an if-else
statement has multiple statements, both branches should be enclosed in curly
brackets.

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>