staging: greybus: spi: add blank line after variable declaration

This patch fixes the following checkpatch.pl warning:

WARNING: Missing a blank line after declarations

Reviewed-by: Alex Elder <elder@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Philippe Dixon <philippesdixon@gmail.com>
Link: https://lore.kernel.org/r/20210519193938.GA7131@ubuntu


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