staging: lustre: convert kernelcomm group to unsigned int

The group variable was converted to an unsigned int in
libcfs_kkuc_group_add() to avoid a potential overflow.
The variable group is used in other kernelcomm functions
so it makes sense to convert the rest of the group
variables to unsigned int.

Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>