UPSTREAM: nvmem: use list_for_each_entry_safe in nvmem_device_remove_all_cells()

Use the provided helper for iterating over list entries without having
to use the list_entry() macro.

Bug: 154188491
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 1852183e142e01cff391b630a7578ff8ddb1a5fa)
Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: Ied3a7cd16d39e1adf977a4f0ca9c3ce23ca080ef