staging: lustre: resolves sparse warnings using static declaration

This patch resolves sparse warnings about non-declared symbol in
staging/lustre/lustre/lov by adding static declaration.
These warnings are like this:
	warning: symbol 'fiemap_calc_fm_end_offset' was not declared. Should it be static?

Signed-off-by: Le Tan <tamlok@live.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>