nvmem: core: fix possibly memleak when use nvmem_cell_info_to_nvmem_cell()

nvmem: core: fix possibly memleak when use nvmem_cell_info_to_nvmem_cell()

Fix missing 'kfree_const(cell->name)' when call to
nvmem_cell_info_to_nvmem_cell() in several places:

     * after nvmem_cell_info_to_nvmem_cell() failed during
       nvmem_add_cells()

     * during nvmem_device_cell_{read,write} when cell->name is
       kstrdup'ed() without calling kfree_const() at the end, but
       really there is no reason to do that 'dup, because the cell
       instance is allocated on the stack for some short period to be
       read/write without exposing it to the caller.

So the new nvmem_cell_info_to_nvmem_cell_nodup() helper is introduced
which is used to convert cell_info -> cell without name duplication as
a lighweight version of nvmem_cell_info_to_nvmem_cell().

Fixes: e2a5402ec7c6 ("nvmem: Add nvmem_device based consumer apis.")
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
Link: https://lore.kernel.org/r/20200923204456.14032-1-vadym.kochan@plvision.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>