UPSTREAM: nvmem: core: fix error path in nvmem_add_cells()

UPSTREAM: nvmem: core: fix error path in nvmem_add_cells()

The current code fails to nvmem_cell_drop(cells[0]) - even worse, if
the loop above fails already at i==0, we'll enter an essentially
infinite loop doing nvmem_cell_drop on cells[-1], cells[-2], ... which
is unlikely to end well.

Also, we're not freeing the temporary backing array cells on the error
path.

Change-Id: I1029a520e86f2c2fd2ad9054037c86b129dde172
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>
(cherry pick from dfdf141429f0895b63c882facc42c86f225033cb)