staging: exfat: cleanup blank line warnings

Fixes checkpatch.pl warnings:

  CHECK: Please don't use multiple blank lines
  CHECK: Blank lines aren't necessary after an open brace '{'
  CHECK: Please use a blank line after function/struct/union/enum
         declarations

Signed-off-by: Valentin Vidic <vvidic@valentin-vidic.from.hr>
Link: https://lore.kernel.org/r/20190902190329.18685-1-vvidic@valentin-vidic.from.hr


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