early_res: Need to save the allocation name in drop_range_partial()

During free_early_partial(), reserve_early_without_check() could end
extending the early_res area from __check_and_double_early_res(); as a
result, the location of the name for the current reservation could
change.

Therefore, we need to save a local copy of the name.

[ hpa: rewrote comment and checkin description ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4B8C7C94.7070000@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>