staging: lustre: ptlrpc: pack_generic: clean up whitespace around parentheses

Fix the following types of checkpatch errors and warnings in
pack_generic.c to comply with coding style:

ERROR: space required before the open parenthesis '('
ERROR: space prohibited before that close parenthesis ')'
WARNING: space prohibited between function name and open parenthesis '('
Signed-off-by: Kristina Martsenko <kristina.martsenko@gmail.com>
Reviewed-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>