classmate-laptop: make needlessly global symbols static

cmpc_accel_sensitivity_attr is needlessly defined global.
This patch makes the symbol static.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: Daniel Oliveira Nascimento <don@syst.com.br>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>