Revert "thermal/drivers/core: Use a char pointer for the cooling device name"

This reverts commit dcf5ffc9 which is
commit 58483761 upstream.

It breaks the Android kernel ABI and is not needed for Android devices,
so it is safe to revert for now.  If it is determined that it is needed
in the future, it can be brought back in an abi-preserving way.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1554f3e0e4972d5553d62dc7b994303708c617b5