staging: r8188eu: Fixed some blank line coding style issues

Added blank lines after variable declarations as per checkpatch.pl

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Chang Yu <marcus.yu.56@gmail.com>
Link: https://lore.kernel.org/r/cf4d4f7a58c9ba4510bed6748f78491c91e3e6f3.1655872968.git.marcus.yu.56@gmail.com


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