staging: r8188eu: replace if with ternary operator

Replace an if statement with a ternary operator, making the code a tiny
bit shorter.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220514164740.282552-5-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>